There are two concerns: The first is whether or not you need to be able to connect to a buddy box. If you do, then you limited to the brands that your instructors are set up on or either you'll need to budget for your own buddy box when you buy your radio. So if that's the case, find out what brand you need to stick to and consider your options.

If compatibility with other people's equipment is not a concern, I'm going to suggest the Graupner radios. They are fairly new to the 2.4ghz radio scene, but the company has been around for a long time with an excellent reputation. Their $159 6 channel radio is head and shoulders above everything else in the market currently in terms of features. Of course, you could pick anybody's 6 channel computerized radio and do just fine with it too. Spektrum is the only company out of the whole bunch that has had ongoing reliability issues, but then again they have so many radios in use that you're bound to hear of one messing up from time to time.