If you want to upgrade to a real radio and have good controls but keeping the tank more or less stock. Go with a barc3 from battle armor. I put one in my panzer 3 and use a 5 channel radio just cause i have it. The tank runs smooth and performs great in IR battles.
If you want to start rebuilding and modifiying tanks and getting fancy like servo recoil or elevation etc, there are more options, but I like the BARC4 i got from battle armor combined with a radio that has a dial knob for channel 5 or 6. Dan over there is tremendous help getting special stuff sorted out.