I have a Martelli 45mm but find it hard to use, but admit that if I used it all the time I'd probably get the hang of it better.
I have and Olfa and one from Accuquilt, and a Fiskars 45mm cutter--all work the same and I frankly see little difference.
I also have a dark blue 60mm--can't remember the brand name, but you can use it with either hand easily and I find that is what I prefer if I'm cutting much fabric and certainly if cutting many layers.