The Fractal stuff is WAAAAAAAYYYYY easier to use than the H90, in my opinion. I had an H90 and at first I was quite excited by it, because it does sound great. But I also shot it out alongside my Axe III, and pretty much everything the H90 does, the Axe III does in spades. You have to get a bit more creative on the Axe III (and shout out to the Helix too, which also is competitive against the H90!) because one algorithm on the H90 is worth at least two on the other units. But once you start stacking stuff up... to me, no question the Axe III kinda destroys the H90.
I found the H90 confusing and frustrating to use. So I sold it. Lost a bit of money on it to be honest, but it is what it is. Recently I purchase the Eventide UltraTap pedal because it was on offer. It is very cool and a lot easier to use than the H9/H90 pedals (obviously!) but again.... it doesn't really do anything I can't achieve on my two multi-fx of choice.
I also found the H90 extremely noisy when doing 4-cable method; particularly when using high-gain sounds on the amp.
Yes I also read that the FM3 isn't quite as performant as the Axe III and FM9 are, when you want to use it for just straight up effects. But I've not had direct first hand experience, just read comments online. Has anyone here directly compared the FM3 with the Axe III and the Helix Floor?? I'd be very tempted to pickup an FM3 at some point if the noise is no worse than the Helix. Just on gut feeling I'm expecting the Axe III to be a little less noisy - it is a little less noisy than the Helix is, but the Helix doesn't bother me at all. It is perfectly fine.
I do agree there is room for an effects-only version of the FM3. Take out all of the amp modelling stuff, and leave everything else exactly the same. Use the now freed up DSP resources to give more delays and reverbs.