Well usually the more control the better.
Usually the difference between 3 and 4 channel radios is aileron or roll axis control.
To turn a three axis plane, you must have a lot of dihedrel (upward bend) in the wing.
With the application of rudder, the plane will yaw to teh right and usually decend. The Dihedrel keeps the plane up right.
With the 4 channel radio, you can roll the plane at an angle then use elevator to pull it through a turn.

Just remember 4 channel gives you more control than 3. 3 channel gives you more control than 2.