AMD rig is better atm.
Base on what I have:
HD 7950: 23-25Mhs stock-overclock
GTX750ti: 10.5Mhs overclock
GTX960: 11Mhs
GTX970: 18Mhs
Which catalyst version do you use for 7950? Which Windows version, ethminer version and frequency for the core/memory.
Windows 7 64 bit
Ethminer-opencl-0.9.41
Catalyst newest version (15.xx) on a website and run 6xGPU_mod to get more than 4 cards on Windows 7
I do undervolt and do not overclock because the rig will stop sometime after 4-5 hours. Don't use Windows 8.1 or 10 if you mine Ether. You'll get a lot of problem.