I've been using Olfas and Fiskars for years.
I bought a Martelli several years ago and could not the hang of it. A friend recently showed me - and boy it's a great rotary cutter - easy on the wrist and the blade is the best I've ever used. I just bought more thru Amazon.
I also recently bought a Gingher, nice hand, cuts well, but not as good as the Martelli.