Specifically, the LG 44" and the Samsung 46". I'm thinking of going with one of these, or maybe I should condider the Sony LCDs for near the same money.

Better brands often use better electronics; processors, pre-in, transformers, D/A convertors. Generic brands usually built to a price which means corners have been cut in places.
Samsung will be a Honda (although in my experience of selling them, without Honda reliability), LG will be a Hyundai and Sony will be an Infinity.

I could almost live with a "Hyundai" compared with my 9 year old 27" Toshiba!!!