Of course we need to think about what we want it to do, now and future. But there are factors: .
The size of a device may affect your ability to use it. Any vision problem needs to be addressed. Often size is important, but smaller devices may zoom up text. That text zooming feature is handled in different ways by different apps. Sometimes with settings, sometimes by widening two fingers touching the screen to expand text, and sometimes with an AAA selector appearing somewhere on screen. Some apps have no zoom at all.
Some Larger TVs can now perform as computers for those who must have a large screen or simply want to access the wealth of internet video.
If you do much writing, more than short emails, a laptop may be needed, although keyboards may be used with most devices with wireless Bluetooth.. The MacBook Air is a great laptop. So-called Transformers are a cross between laptop and tablet, with keyboard. A very few old laptops actually work as transformers (Asus 10” notebooks).
If you travel or even move around much, You will want a 7” device or less. If you travel a lot, a smartphone is needed. I like the big 5” smartphones
3G or 4G
3G offers access in many more places than Wi-Fi but costs $$$. You can “tether” a device to your smartphone's 3g or 4G.
The iPad offers a fine front camera with editing. The Nexus has a back facing camera for phoning (Skype, etc).
Smartphones generally have GPS. The Nexus has GPS. However, for traffic you need data service, 3G or 4G. I recommend 4G. Traffic service is free with the WAZE and Google Maps apps. I use both of these to get local reports and map route traffic (red, green routes etc.). I would not want to travel without either.
The right apps are very important, although Apple and Android devices have a huge selection. However, if you want iTunes U (lectures from the leading colleges and universities), choose an Apple iPad. For camera and photo editing the iPad is probably the choice.
A smartphone is handy (really almost essential) for travel needs, or any smaller device with 3G or 4G., though selected airports and hotels have free Wi-Fi.
Windows and Mac systems are converging and synced with tablet and smartphone. Users with Gmail will find much is already synced. Apple is converging its products, as also Windows in October. If you have either, the upgrade is CHEAP if your old computer can handle it.
Recorded TV requires a good internet connection. Live TV is even more demanding and may require a separate device, My smartphone does not handle TV well.
Apple is known for its quality support in stores, including “how-to” courses. Barnes & Noble also supports Nook in its stores. Microsoft offers very good online support. For seniors Tap or Click this website.
So far no one device will serves all needs, but that is true of clocks and radios and TVs. For many, a laptop and tablet will suffice, and even take over clock, radio, and some TV.