With that size/s in mind only two things to consider
1. Size of your budget as mentioned.
2. Size of hole it will fit into.
The second is probably more critical than the former.
The number of folk I have come across who have gone for a 'Big' screen because it looked awesome in the store and found it overwhelmed their 16 x 12 lounge.
So size it first a 23 inch probably needs 26/28 inches to sit in comfortably- then go pricing one.