Personally, I love the Saitek X52. There's a "Pro" version too, but I haven't tried that one.
Lots of buttons on the X52, and I can fly/fight without taking my eyes off the computer screen since I don't need the keyboard to operate any flight-related functions.
The only downside I've found is that I'll wear out a button or two every 10 months or so. I buy it with the two-year replacement plan though, so I just take it back to the store and swap for a new one when that happens.