Try checking out sites like www.timhiggins.com
for current product reviews. The Tim Higgins/Tom's Networking site is especially useful in making product recommendations.
Over the years I've used an Apple BaseStation, a Milan ShAir Office, an Apple Airport Extreme, a Linksys WAP54G, and a Buffalo WLA-G54. Each has had its own little feature & performance quirks. Out of these, I still use the Airport Exreme and the Buffalo. The Buffalo (although it has a quirky interface) is probably my favorite as the performance seemed a little better (just my empirical observation w/ no hard numbers or tests) than the others.
Try doing a product/review search on the Tim Higgins site, there is probably a lot more test data on there now than when I last checked (months ago).
As for the question regarding the wall....err....kinda depends on what is in your wall. i.e. if there are steel frames/studs then it *could* affect wireless performance. In addition, the reception angle through the wall or corner of the room can also affect performance. I believe you can find a few articles on this subject on www.timhiggins.com
under the "Need to Knows" section. The one you may want to read in particular - "Wireless LAN Performance Improvement", as I think this one deals with the topic of range/speed vs. interference.
Hope this helps!