You need a poll on this thread with the short list of what you can buy depending on your budget.
If budget were no issue to me, I'd go with the Thrustmaster T500RS, otherwise I might consider the Fanatec CS Wheel Base with M3 GT2 Rim, but I feel that even if this set is superior to the T500RS (which is debated), with pedals its a much dearer premium and not officially supported.
I have and used the DFGT, and I love it, I mean what more can you want? It's simple, beautiful construction, excellent DS3 buttons on the steering wheel, nice shifter buttons, direct feel, and decent pedals.
I upgraded to the G27, and its better, yeah, but its only better overall, there's tradeoffs, it has metal shifters, leather wheel and a clutch pedal, and a gate shifter, but considering the clutch in GT5 is wooden that's out, the buttons are on the shifter which ergonomically is far worse, and because of the external shifter there's all these bloody wires, can be a nightmare without practice.
There's lower end Fanatec products too, but again the value doesn't make sense to me.
Can't go wrong with DFGT or G27, both are so cheap these days, and you might as well get the G27, fingers crossed by GT7 there'll be a real clutch and the wheel will still be supported, but if the DFGT is super cheap (sub $80 idk), its an astonishing wheel with benefits in its own right.