What to look for when deciding on a new unit?

Let me start by saying I'm not a car audio enthusiast and I'm looking for some advice to help me make an informed decision and purchase.

I have a 2002 Chevy S-10 with factory stereo and I'd like to upgrade the receiver to something with a front USB and front 3.5mm aux jack so that I can charge my cell and hear the audio from it through the stereo for both conversations and when I stream Pandora.

Musts: CD, USB, front Aux.
Wouldn't Mind: HD, detachable faceplate
Budget: Would like the head unit to be under $200

My problem is that there are dozens upon dozens of models that all seem similar, and I'm at a loss as to how to differentiate them. For example, the Sony GT 640/540/440 series all seem almost exactly the same. Is there something I should be looking for or perhaps something I should avoid at all costs? I'm really happy with the sound and features of the stock radio, the reason for the upgrade is that I can't stand the alternator whine I get from using FM transmitters in my accessory plug and want a cleaner less cluttered setup.

I won't be installing it myself, and will probably be purchasing from a local store like Fry's or such, but any help is greatly appreciated.

 

Thanks for the replies!

Nope, just looking to replace the head unit. Speakers amps and everything else will remain the stock ones.

Thanks for the recomendation! Any reason why you choose it over the multitude of others?