Depends how fancy you want your kit.
As a basic joystick, the FLY 5 is a reasonable one, but it can get a bit loose.
The X52/X52 Pro is OK, but still cheaply made plasticky kit.
The X55 is slightly better, but I've heard about so many having faults, breaking, giving up and just outright karking it that I was strongly dissuaded in the end.
Saitek have some pretty good customer support for the X55, but that still isn't very good when so many people have had to contact them in the first place.
Obviously top-end would be the Thrustmaster Warthog and you definitely get your money's worth. However it is a copy of the A10 Warthog controls and great if you play such a flightsim, but it didn't feel appropriate for flying a spaceship. I also found a few personal niggles with regard to switch/button placement and felt the throttle split was quite uncomfortable after more than about 20 minutes.
Personally, I went for the CH Fighterstick and Pro Throttle.
The pair can be had for around £200 new and, while they are of very old design, the fact that so many people are still using their original 80s-made ones is testament enough to their build quality.
Function-wise, the setup is comparable to the Warthog. The feel is very light, but some people prefer this as it makes fine corrections a lot easier.