I think any of them will work but I think the Samsungs pick up over-the-air TV signals better. We've been bouncing around a couple of Samsungs for three years and they've sat outside in the MH down to -20F and up to 115F inside of the MH with out heat or air on.
We primarily went with them because we like their "smart" capabilities the best. If you want more than just a TV, read the functionality carefully. Each brand makes from just a cheap TV to a multi-function TV. You will have to pay more if you want more functionality.
As for where to buy, we've gotten some from Costco and Best Buy who will match Amazon's pricing so you don't have to wait for delivery. I think Costco has a better warranty, but I've heard they're changing it because of people buying them to use for a party or something like the superbowl and then returning them a couple of days later.
Bill