My Dad asked me recently what sort of computer he should buy to replace his ten-year-old HP laptop. And what sort of phone should he get to replace his old Nokia? And while I was at it, should he get one of those tablet things?

There are a lot of possible options at the moment, because all kinds of devices from smartphones to traditional PCs have become broadly capable of doing the same work, and because a whole raft of new Windows 8 laptops and convertibles have just arrived to clutter up the shelves.

Therefore I’d suggest mostly ignoring the nominal capability and specs of any device, and considering instead how it feels to hold and operate and what ecosystem it is part of.

Let me explain, and then give some more concrete advice.

Ecosystems

This slightly absurd term describes a set of services and systems that work together, many of which are likely to have been provided by the company that made the device’s operating system.

Increasingly, when you buy a device, you are making a decision to participate in its maker’s ecosystem: it will make your life easiest if you are prepared to use backup, file and photo sharing, music download, email, mapping, browsing, app installation, and other services all from the same supplier.

For example, if you buy an Android device, you’ll be most content if you also use Google mail, maps, marketplace, etc. Buy a Mac or an iPhone, and you’ll have the happiest time if you use Apple services wherever they exist. Windows 8 and Windows Phone expect you to have a Microsoft account and to use it. If you have two devices, say a laptop and a phone, they’ll get on best if they’re both within the same ecosystem as well.

You can make a conscious decision to mix and match—I do that myself, somewhat, because it pains me to side with any one megacorporation more than I have to—but it can be heavy going. If the idea of understanding what you’re doing and why you’re doing it appeals to you more than having an easy life, then install Linux and subscribe to no single ecosystem; I’ll be happy to help out. But I’m guessing you don’t really want to do that.

So no, the usual thing seems to be to decide which company you dislike least, then let that one have your credit card details and as much goodwill as you can muster. And that means picking one of: Apple (with OS/X and iPhone/iPad), Google (with Android), or Microsoft (with Windows and Windows Phone).

“Feel”

Modern computing devices, from smartphones to PCs, are increasingly touch-driven (either through a multi-touch touchpad or a touchscreen), portable, and versatile. The way you hold and interact with them does matter.

I’d strongly suggest you start by trying out the best devices you can find from each ecosystem, hands-on, either by borrowing from a friend or in a very relaxed shop. Decide which one you enjoy the basic interactions with the most.

If the design, interaction and animation (and materials and heft, for specific devices) please you every time you pick it up, you’re probably going to be happy with it. If they annoy you, you’re not. If it’s ugly and inconvenient now, it’ll be ugly and inconvenient in five years’ time.

The options

These are the things you can buy at the moment.

Laptops you know. They run either Windows (if PCs) or OS/X (if Macs). Some of the Windows 8 ones now have touchscreens, but not all of them (and nor do any of the Macs).

Tablets such as Apple’s iPad, the Google/Samsung Nexus 10, or the Microsoft Surface are slatelike touchscreen devices in which a separate keyboard is strictly optional (there is a “virtual” one on the screen). They typically run one program at a time, full-screen, rather than having multiple separate windows side by side, and the programs are redesigned for touch rather than mouse operation (the buttons are bigger and they have fewer menus, for example). All software is installed from a central “app store” run by the operating system manufacturer.

Smartphones are small tablets that can make phone calls. Most mobile phones nowadays are smartphones.

Things to bear in mind

A modern smartphone is a computer. It can do practically anything, but it’s sometimes fiddly because of the small size, and it has amazingly awful battery life compared with a classic mobile phone—be prepared to charge it every day. If you buy a nice new phone and make use of it as a handheld computer, you’ll probably find you use your laptop less.

Tablets overlap with both smartphones and laptops. If you have a smartphone, the laptop or tablet is likely to take jobs like “reading long documents, and doing anything that needs a lot of typing”. Don’t buy both a tablet and a laptop, just make sure whatever you get has a good clear screen and you can stand it up on a desk and type with it.

Proper keyboards are available for every kind of tablet: you can always get something you can either plug in or attach wirelessly. But convertible tablets (with a keyboard stand included, like the Asus Transformer, right) are nice too. They’re very like laptops to use and can be folded up and packed away the same way, but you can also pull off the screen and sit on the sofa with it. Most run Android.

There are also small tablets, but… While the iPad, Nexus 10, Transformer series, and Surface are in the 10-11″ diagonal range, there are also several in the 7-8″ range like the iPad Mini or Nexus 7. The small ones are natty and better for carrying around, but less good for sofa-surfing and can’t really replace a laptop.

If you’re buying an Android device, look for Android 4 or newer and get a Google Nexus if you can. They sell a phone (the Nexus 4), a small tablet (Nexus 7) and a big tablet (Nexus 10) and they’re all pretty good. Being Google’s “own” devices, they have good compatibility and more updates. You can’t generally get them through mobile network contracts though.

Don’t buy an Amazon tablet. The Kindle Fire series are really designed for only one thing: consuming content from Amazon.

If you’re buying a Windows 8 laptop, get one with a touchscreen. Windows 8 makes very little sense without a touchscreen. You can still use a mouse as well.

Windows 8 is extra-confusing because of the existence of both Windows 8 and “Windows RT”. These are essentially the same, except that Windows RT can’t run any “legacy” Windows software apart from Microsoft Office: it only runs touch-optimised full-screen apps from the Windows app store, of which there are not all that many available yet. Windows RT is found on tablets and some laptops. It’s a perfectly capable operating system, but there’s a big risk of disappointment if you want to run arbitrary Windows applications from around the internet and discover too late that you can’t.

So the range of applications available matters, but it’s not the be-all and end-all. Off the top of my head: Apple’s iPhone has the most apps, then Android phones, then the iPad, then desktop operating systems (Windows, OS/X), then Android tablets, and in last place Windows Phone and Windows RT. Numerically the difference from first to last pretty big, but it can be oversold: in practice you won’t find many things you can’t do, nor run out of new stuff to try out, on any of them.

You can safely ignore any review in which the star rating appears to be correlated to how fast the computer’s processor is. That’s practically irrelevant nowadays. Do test how smoothly the screen scrolls and zooms though.

Don’t forget to check whether you use any software that absolutely must continue to run on whatever you replace your laptop with. In most cases, all you need is software that does the same sort of thing (it doesn’t have to be exactly the same software) but you don’t want to get caught out if there’s anything specific you rely on.

The whole mobile-network contract business is an extra layer or three of bafflement that I can’t really help with. I generally buy hardware unsubsidised and stick a pay-as-you-go SIM in it.

Some suggestions

Give each of the ecosystem contenders a test run, and then, from the options below, pick the phrase you most agree with and read that bit!

(Although by the time you’ve given each them a test run, you may well already know what you want. That would be a good outcome.)

I’m totally ignoring price here, although sadly the most interesting options almost always turn out rather expensive.

“I really like the way the Apple things work” Well, that was easy. If you’re dead set on having a laptop or you want as much flexibility and control as possible, then you want a MacBook Air (probably the 13″ size, although the keyboard is just as titchy as the one in the 11″). Otherwise, get an iPad and forget about the laptop. Either way, buy the laptop or tablet first, then think about phones (the phone to get is obviously an iPhone, it’s just a question of which one and that basically comes down to price).

“Windows 8 and Windows Phone appeal to me, and I don’t think of Microsoft as an objectionable enemy” You’d probably find a Windows Phone 8 phone (any one, though the Nokia Lumia 920 has the most lovely screen) and a touchscreen Windows 8 laptop a good combination. Look at the Lenovo Yoga 13, which is a fine laptop that I predict will sell half-a-dozen at best because of the weird way it’s being displayed on a stand in the shops (the screen flips back to make it resemble a large and heavy tablet, but it’s really a laptop). Or consider the Samsung Series 5 Touch laptop or possibly the ATIV SmartPC convertible. Although Microsoft’s Surface RT is a beautiful object that I’d like to recommend, it isn’t yet quite the laptop replacement it thinks it is. There’s a Pro version due out in a few weeks that might be worth a look, though.

“I use a few Google services already, and I’ve tried at least one Android device I thought was nice to use” An Android tablet convertible like the Asus Transformer series can in principle replace a laptop quite well. Try one out, but if you’re thinking “hm, maybe Android might work” it’s probably cheaper to give it a go with a phone first. Google’s Nexus 4 is the obvious choice if you can find one.

“Those touchscreen laptops and tablets are all a bit small, I like my bigger PC” There are some reasonable touchscreen laptops with somewhat larger screens, including several from HP like the Envy TouchSmart 14. I hesitate to recommend one because I’ve actually never seriously used Windows 8 with a touchscreen on a larger screen. It might be a bit tiring. Do try it though.

“This is still all too complicated” Then stick with what you’ve got. The new Windows 8 machines have only just come out, and everything will look a bit simpler in six months’ time when the disasters have subsided and the new-fangled things have got cheaper.

What would I do?

If: money was no object; I had no corporate loyalty and lacked my affection for open Unix-type systems; I wanted to be able to do anything except programming; I didn’t have a laptop, tablet or smartphone already; and I didn’t mind if my phone was too big to fit in a small pocket… I’d buy a Nokia Lumia 920 and a Lenovo Yoga 13.

That’s because I like the Windows 8 look and feel, the different Windows 8 devices work well together, and both of these are attractive well-made objects that are a pleasure to use. I’d pick the Nokia over the otherwise excellent HTC 8X because of its better screen and camera and the inclusion of Nokia maps with navigation.

But in real life, I couldn’t afford that. If I wanted to keep the price down a bit and avoid being too locked in to any one ecosystem, I’d look at a Samsung Series 5 touchscreen laptop and a second-hand unlocked Google Nexus S phone from eBay. But I would go and have a play with a Surface RT tablet in John Lewis first, just in case. It’s a nicer physical object, for all its limitations.

And if money was the object—if it was the main thing that mattered, but the other conditions were the same—I might buy the entry-level full-size iPad and nothing else. It’s much cheaper than a touchscreen laptop and has a lot of software. I don’t really go for the visual design, but it’s cheaper than the alternatives I do really like, the basic interaction and feel are fine, and having all those apps available counts for a lot.

Of course, being a typical human creature I’d really do none of the above. I’d just buy whatever I happened to like the look of on the day and rationalise it afterwards. I trust you’ll do the same!