I have a laptop with a 970m. While it's nice, the fan gets really noisy when I'm gaming. If I had it to do over, I'd get a laptop with a mid-tier GPU like a 950m or 960m. Then a desktop with a GTX 970 or 980. Use the laptop's built-in GPU when on the road. At home I could game on the desktop or (if I wanted to game on the laptop) use something like Steam In Home Streaming to run the game on the desktop but display it on the laptop.
Also note that despite the numbering, the 970m and 980m are substantially inferior parts compared to the GTX 970. The GTX 960 uses a different core so isn't exactly comparable, but is probably about the same speed as the 970m after you factor in clock speed.
970m = 1280 shaders, 80 texture units, and 48 render units.
980m = 1536, 96, and 96 of these respectively.
GTX 970 = 1664, 104, 56, in addition to being clocked higher.
GTX 960 = 1024, 64, 32
960m = 640, 40, 16, on an older core.
https
/en.wikipedia.org/wiki/List_of_Nvidia_graphics_processing_units#GeForce_900_Series
https

/en.wikipedia.org/wiki/List_of_Nvidia_graphics_processing_units#GeForce_900M_.289xxM.29_Series
Why Steam In Home Streaming? Because it'll let you do crazy things like game for 8 hours on the laptop on battery (because the game is running on the desktop and for all intents and purposes the laptop is just playing a video).