Go for the Samsung.
why? :
LG. its the worst. we had a 29" LCD TV and the touch buttons gave up after a month, and then the TV stopped working after 3 months.
Sony Bravia, the picture quality is better than samsung, but if your watching something through a pen drive. it only supports AVI though it claims it supports everything havent given much trouble other than that.
Samsung is the all rounder for me, reasonably good picture quality, supports even FLV through a pen drive and we have made in india samsung LCD tv in our house in india and been using it for over 4 years. still no problem.
Try to find a Korean 42" Samsung TV. we got one from Dinapala 2 years back. its almost 18 hours switched on daily. and still no issues at all.