'Get the best radio you can afford' is great advice, especially if you're a geek like many of us. I've never regretted 'overbuying' and growing into the radio.  Even a Stick-type plane can use 7 or 8 channels: split elevators, 2 aileron servos, 2 flap servos, etc.

OTOH, if all you plan to do is fly normal 4-channel stuff for 2-3 years, buy a 6-channel computer radio at the very least.