Like dolphin said, it depends on what you're doing. Of course AWD is always the best (unless you want to do drifts). Other than that, it all depends.
With RWD, you have more theoretical traction than FWD, since your 2 tasks (moving foward and turning) are shared between the front and rear wheels. The problem with that is, that there is usually not enough downforce over the rear wheels to keep them from sliding out. The end result is that you'll lose traction easier in most RWD cars than you will with FWD cars on a hard corner. And basically, no matter how good you can control it, your ass end swinging out on every hard corner is slower than it not swinging out. However, there are certain situations where having your ass end swing out could be an advantage, and the only way you can really do that with FWD is with the e-brake...which still works fine.
Now let's talk FWD. Corners love them. Tons of weight over the drive wheels...you throw it into a corner, and it pulls right through. Your less likely to have your front wheels on a FWD car lose traction on a corner than you are your rear wheels lose traction on a RWD car.
BUT, with FWD, you have less theoretical traction, because the front wheels are doing all the tasks of the car (accellerating AND turning). And ALSO you have what I think is the biggest problem...traction off the line/wheel hop. 0-60 times on FWD cars pale in comparison to those of RWD and AWD cars.
So really, it all depends on what you want. If you want a drag car...RWD or AWD is best.
If you want an autoX car...FWD or AWD.
If you want an all out track car (to take on a road course), they'll all do the trick, but it really depends on the car.
Keep this in mind between AWD and RWD. According to Road & Track's article (I think it was R&T), it took a $150K RWD car (the Ferrari 360 Spider) to achieve what the $18K MP3 does in the slalom. Food for thought.
