First off, both your TV displays choices are pretty good for your price range, though I feel there are some pros and cons to each of your choices. The Vizio is more popular because it is marketed almost solely to large end retailers, such as, Walmart, Target, Kmart, etc. So it is obvious that is would be more widely purchased by consumers across the board. But, I don't feel that this makes the Vizio a game breaker. To me, I would say the overall the Panasonic would be the better quality choice. I say this because in a lot of your criteria for these displays are equal on paper but, Panasonic has a better track record of more quality products as far as their TV Display line goes. Each Display has a refresh rate of 120hz which is standard at this size TV screen. When it comes to Visibility, there are some differences that may be deciding factors on your TV debate. Vizio has less of a glare with its semi-gloss matte finish as compared to Panasonic's new version model with a screen that has some reviews about glare being an issue. This should also should help shed light on viewing angles and display placement in the room you will be operating it in. Be mindful that if you have a sunny or natural illuminated room there are more chances that the screen will be affected by this. I know you said your price range is limited between $800-$1000 but, take a look at Samsung's line of L.E.D.'s. They are really on the cutting edge for quality, innovations, and service. Hope this helps you out.
Lead AV Tech, AA Rental