Well depending on the size room you have the lg is 10 inches smaller. The Vizio p55 is on sale for 899.00. that's over 1000 cheaper . Also if you're going to do a lot of gaming on a television input lag is really important. The lg was tested at 53ms of input lag. The Vizio was tested at 17.3. that's a big difference ..The 65 inch version of that lg TV is 3500.00. also the lg does not support dobly vision.
Here are the reviews for both ...
http://www.rtings.com/tv/reviews/lg/ef9500
http://www.rtings.com/tv/reviews/vizio/p-series-2016
This years OLEDs do HDR10 and Dolby Vision out of the box, no waiting for a firmware update like people who bought the vizio are doing. I paid $800 more for a 55 OLED over a 65" LED but it was well worth it IMO. Now I just need a UHD player.