I like BWI a lot. The food is not too bad, it's easy to get around and there's plenty of space to sit. I find it clean and perfectly fine.
My Opinion:
PHL = a dump
Norfolk = Getting Old but good in-and-out.
Hartford = Getting Old
Providence = Is pretty good.
Tampa = Nice but there's few food and store selections when in the terminal.
PITT = Not too bad.
Manchester = Like it a lot. Smaller but easy to get to and clean.
BOS = Another big city airport with not great access.