The following link is a little dated, but should give you some basic features to consider when making your selection:
Which surface radio system is the best?

For me, the single most important feature is "Steering Speed", many budget systems will not include this feature and I have found it necessary to adjust the speed of faster servos where many pros recommend a servo speed in the 0.08 - 0.12 sec/60° however everyone's reaction time is different and slows as you age. I'm in my 40's and typically use around 88% steering speed on my 0.08 servo with a fresh set of tires, as the tires wear I might increase the steering speed up to 92% as they start to push or if traction is down due to track conditions, etc.

I would caution that I have ran into issues with some Spektrum radios not being able to get the steering speed feature to work properly when assisting other drivers at the track with their radios. Most folks had no problem using this feature with the same servo/ESC and switching to a different brand of radio.

In no specific order these are some of the most popular brands of radios I see in use in my area by some of the faster drivers:
* Airtronics/SANWA
* Futaba
* Graupner ( I currently run the X-8E, great system with Rx's for about $30)
* HiTEC
* KO PROPO