id go with the m15x.. the parts are cheaper and faster on the higher end ones.
a i7 920xm is around 100 would be faster then the newer i7
a r9 m290x is around 150ish and it would smoke the 650m
and intel hd is not a gpu they are shit
refer here http://gpu.userbenchmark.com/Compare/Nvidia-GTX-660M-vs-AMD-R9-M290X/m7749vsm11722