I realize this response is super late and you probably already bought one or the other.
I bought the LG 47LS4500 on New Years and set it up. The size was great and the picture was very solid. After playing with it for a while I realized it had no "soap opera" effect. I started doing more research and discovered LG's "trumotion" was not the same as Samsung or other Tru Motion 120hz. I don't want to watch all my shows with the soap opera effect but I do want my sports and games to be AS SMOOTH as poosible. And more importantly, 1) I want the choice to turn tru motion on or off and 2) I want a product as advertised.
With the LG there is no advanced picture setting to turn the trumotion on/off. Apparently, it is just an automatic adjustment within the software. So, even though it is advertized as 120hz - you are often times (from what I experienced) just getting a 60hz image. This might be fine for many consumers - I know many don't want the soap opera effect, or even to mess with it.
SO, I kept it a few days to see how bugged I really was and decided to take it back. I purchased the Samsung UN46ES6003 and LOVE it. It is noticeably smaller (1" makes a difference on the overall size) but it is still big and the picture is far superior. Plus you have more control, I feel, over your picture settings. I paid a little over $100 more for the Samsung (from Walmart) and am not bothered by the price at all. It was well worth it. I love the TV. Also, the speakers on the Samsung, although no sound bar, are better than the LGs.