I do wireless consulting for a living, but the 3G and LTE kind that makes your smartphone work. Different technology but the principles of RF are the same.
I agree with the statement about Apple. Great products but a bit more expensive.
The primary difference in all the stuff you'll see on the shelf at the local Best Buy or whatever is (a) the network processor and (b) the power level on the Wi-Fi radio. What almost every single company in the consumer space does is make minor tweaks so they can take the same basic product and sell a differentiated low/medium/high version so they can make more money. Give Apple a little credit for just deciding to build a single option.
So the network processor is important as it is ultimately the bottleneck. It handles sending data between devices within your home network and to/from the Internet.
With Wi-Fi, the power level affects the capacity and coverage area. Lower power is worse, higher is better.
So my advice is the following. Don't buy the low-end model from anybody. It's garbage. Most people will be fine with medium level if range isn't a problem. The higher-end stuff is going to cost more but will also reduce the likelihood you'll be frustrated later and will give you a little more future-proofing.
And when I say high-end I'm generally talking about stuff in the $100 and up price range.
I just went through this with my father-in-law. He went cheap and now he's spent more money to add wireless repeaters than if he took my advice the first time.
Also the major feature I would look for is the ability of the device to automatically assign the radio channel based on the channels used by your neighbors home routers. 99.9% of the population don't understand the concept of frequency reuse and channel planning. That's why the 802.11 spectrum is "polluted". Apartments complexes are like radio cesspools.
Everybody has a cute marketing name for it so it's hard to say what to look for on a box.
And as far as 802.11 versions, you should be fine with 802.11n.
Full disclosure. I work for a company that recently sold off it's consumer products division.