M7 is better built with it's full aluminum build, though the G2 feels better due to its curves
The speakers on the M7 are great blow anything else out of the water.
Screen might be just a bit better on the G2, but the M7 has a great screen anyway.
The G2 has great battery life, much better than the M7
People have different opinions on the camera, the M7 is better in low light, but the G2 is a better all-around performer.
Sense is better than LG's skin, but that's just my opinion.
So it's up to you to choose what suits you best really.