T500 would be the "best" but they have yet to come up with a shifter to go with it. This is the most expensive.
Fanatec GT2/GT3RS (same thing except one is XBOX compatible, but who cares right?) would probably be second best, being a little cheaper than the T500, and at least there is a shifter and clubsport pedals optional. Downside is the waiting time to get one.
Logitech G27 (newer version of G25) is the cheapest of my top 3. Shifter included but the buttons are not mappable meaning the wheel isn't fully supported by GT5, but it works.
If these are too expensive, you can aso use a G25, Driving Force GT, or Driving Force Pro which are good, but not that great. Need more details, search like I did.