Care to expand a little on your choice?

Where is "home" in Florida, or in the DC area? AA, for instance, flies DCA-MIA 8 times a day, and has a pretty good sized operation at DCA, and wonderful folks that run the AC there. It's my favorite DC area airport to fly into. If you live out near Dulles, though, it wouldn't be a useful airport.

A lot still comes down to how many miles you expect to fly each year, and "where" you expect to fly. Each carrier offers perks that can vary depending how much you're going to fly. There's not enough information in your post to see who would be the perfect fit for you.