It's been over a year since I paid careful attention to LCD TV sets, but I can state that not all TVs within the same brand perform the same. You really need to go look at them in person, side-by-side, and you often have to dork with the brightness and contrast to undo the mess created by the previous store patrons.
That said, the Sharp Aquos 45" is amazing. In smaller sizes, Panasonic also makes a number of good LCD panels. When I was doing side-by-side comparisons, I liked the Panasonic panels better than the Sharp ones in terms of black levels and color saturation. Today, of course, it's a different generation of products, so I hesitate to make any categorical statements.
If you're not persnickety for the ultimate in image quality, another relevant feature to look for is a built-in ATSC tuner (as opposed to earlier panels which are "HD-ready"). In theory, you can plug such a panel directly into an antenna and have HD right away. Likewise, a feature that I haven't seen but would be looking for is digital audio
output. Flat panel TVs have, if you're lucky, barely acceptable speakers. If you had digital out, then you could connect the TV to your favorite home theater receiver. Or, for a more compact setup (e.g., in the bedroom), you could get something funky like Yamaha's
YSP-1 speaker array.
Finally, pay attention to the quality of the user interface, the remote control, and all that. Once you've been spoiled by a TiVo, it's amazing how awful most of these new TVs are.