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 7PXR 7-Channel FASST Transmitter With R334SBSE Receiver by Futaba Systems is quality built for high performance use. Shop RC supplies, parts and other hobby products at Tower Hobbies.
www.towerhobbies.com
I'd just leave the SCX24's on the RTR controllers.