But I'll thrown in another thought for free - the X-100 is a camera that people want to use, whereas the Eos-M is a camera many people purchase simply because it is heavily discounted.
And then discover that they want to use it. There's a reason that the M, which has practically been forgotten by Canon USA, has such a strong following. I was one of the people who was hesitant about buying it even at the heavily discounted price, only to end up loving it and using it as much or more then my DSLRs.
And to the poster who claimed the Fuji 'blows away' the M on IQ: the X100s is a little bit better at high ISO. There's no real difference any where else. (What is it with photographers and hyperbole? "Blows away" would be a 5D3 at 3200 vs. a 20D at 3200. Tiny differences most will never notice even in huge prints != "blow away.")
As I see it there are three major differences between these cameras that would determine OP's choice.
* Viewfinder. M has none, X100 has one of the best. I find I do not miss a VF on the M, though to be fair I have DSLRs and use those with subject matter where I probably would miss a VF.
* Analog vs. touch screen control. This is a matter of personal preference, though admittedly most would prefer more physical controls. I like the M's touchscreen, but I do wish it had 2 dials for directly accessing shutter and aperture in manual mode.
* Lens interchangeability. Fuji X100s has one lens, the M has 3 dedicated and can take hundreds more via adapters. Notably, it is 100% AF/AE/aperture control compatible with Canon's EF/EF-S lenses via adapter.
Just depends on what you want out of the camera.