I'd honestly look at the FlySky line. That little GT5 I bought for my kiddo is really impressive:
Another plus is the receivers are about half the price of the Futaba/Airtronics/Spektrum.
This is the Futaba comparable to what I run (mine is the 4PLS, they don't make it any more):
Amazon.com: Futaba Systems 4PM R334SBS 2.4GHz 4 Channel Surface Transmitter, FUT010043873: Toys & Games
www.amazon.com
....or just go all out and get this guy
. This is what I'd be using if I was still racing:
The Futaba Systems 7PXR 7-Channel FASST Transmitter With R334SBSE Receiver is a great brand at a great value. Find RC transmitters, radio systems, and electronic RC parts at your online hobby store, www.towerhobbies.com!
www.towerhobbies.com
I'd just leave the SCX24's on the RTR controllers.