Do a google search on "best tv's" and you'll find scores of sites that perform reviews of the most recommended tv's available. You'll get a much better unbiased selection models to look at. Look at more than just the first one or two sites, and you'll start to see a pattern of the few that are recommended the most by many of the sites and you can go from there. You'll obviously need to decide how much you intend to spend on the new TV, that should hopefully help you slim down your choices.

As far as size, I always recommend getting the biggest size you can comfortably fit in your space, and more importantly, that you can afford. I think 65" is now the standard size. They only seem big for a day or so and then you forget about it. Make some cardboard mock-ups of the two different sizes and put them up where you intend to put the TV.

I have had several different brands including Vizio and Samsung, I prefer Samsung for the picture quality and reliability. As to size vs. picture quality, with 2 TVs of the same brand with identical specs, the smaller should have better clarity. Think 50" vs. jumbotron. However, your unlikely to see much of a difference between 55 and 65.