I've worked in consumer electronics for the past 3 years, so I've seen my share of TVs come and go, so here's what I think based on what you've told us.
You're probably looking at an LCD. At those sizes, LCDs are going to give you a lot more choices because plasmas are hard to manufacture in smaller sizes, so you usually see them in the mid 40s-60s. They certainly exist smaller, but not in as great of numbers. I personally like the plasma's picture better because you get a better deep black and because they have faster video processors, but at a certain point it's just nitpicking personal preference, ya know? My favorite TVs of all are DLPs, which aren't true flat panels, but I like to be different
Sonys are supposed to be the best LCDs on the mass consumer market, but I've never been allll that impressed with them, and to a certain extent, you buy a name when you buy a Sony because they ARE marked up because of brand recognition. As for the other brands mentioned in this thread...
Samsung - definitely my favorite brand, I have a 50" DLP in my living room and a 20" LCD in my bedroom and would definitely stay brand-loyal to Samsung in the future. They make both LCDs and plasmas (unlike Sony, who make only LCDs and Pioneer, who make only plasmas) and I've never seen a Samsung that wasn't bright and clear as far as picture quality goes. Their exterior design is also very clean and modern, which I prefer to the 8 tons of grey plastic that Sony likes to put around their tvs.
Sharp - their TVs are massively underrated, i don't know why they're not talked about more often. Our store has never had service or return issues with them, they're the kind of TV that "stays sold." Their pictures are very crisp and bright, and I don't think I've ever seen one that looked bad. If I had to stray from Samsung, I'd go Sharp for an LCD.
Vizio and LG - I'm not a fan of either of these brands, although LG is starting to step their game up a bit. Most of the time when I see them, even if they're 1080p, they don't look as clear as my 720p DLP. In my opinion, their deep blacks usually don't look as good as some of the other brands and and although both are usually a little less expensive than the other brands, if you're going to spend that much money on a tv in the first place, spend the extra hundred or two hundred bucks and upgrade to another brand.
Another thing I would recommend is that you don't take the advice of things like Consumer Reports as the gospel truth, because although they're sometimes accurate, other times what they recommend is the exact opposite of the reality that I encounter everyday while interacting with customers and getting feedback with their experiences in their home with the product. For example, last year they recommended an Insignia tv very highly, when I know for a fact that those tvs are returned often and customers are often dissatisfied with their picture quality and performance.
Also, the adage "you get what you pay for" doesn't always hold true, but flat panel tvs are NOT cheap to manufacture or ship, and the types of components they use and the type of manufacturing practices they employ may very well be reflected in the price of the tv. if a manufacturer can wholesale a 46" LCD cheap enough that stores can carry it for a bargain price, the corners are getting cut somewhere, kwim? you have to decide whether or not the deal (and the gamble it entails) are worth it to you.
ultimately, just go and look at the tvs! more often than not, you'll find a picture you just can't stop looking at. regardless of what brand it is, THAT is the tv you should get.