I've used both, as well as the ergonomic handled rotary cutters and I find they both do the job and I often switch off, depending on whether or not I have put them back in place. I'm afraid I have a habit of putting something down and then having it disappear on me, probably just me and/or early old timer's. LOL.

I have one of the old Fiskars grey rotary cutter with the orange release button, I like it and it works for me. The newest Fiskars cutter is much more difficult to open and close, the design has been changed. If you've got arthritic fingers/thumbs,
this isn't the cutter for you. I still like the ergonomic Olfa cutters the best. I prefer the 45mm for most cutting jobs, but for multiple layers, the 60mm is a better choice.
Sharon in Texas

Will I be able to cut through 4 layers of fabric with the 45 mm Olfa ergonomic blade?? Should I have ordered the 60mm one??

I continue to purchase the ergonomic Fiskars with the 45 mm blade. They just fit my hand comfortably. I like that the button to retract the blade is right at my thumb. I've also used a straight Olfa, but didn't care for it. Maybe an ergonomic one would be different. I also have one of those green ones, Clover, I think, which was in a basket of quilting goodies I won. I've never used the Gingher or met anyone who does, so haven't been able to test drive one. For me, the cost of a Gingher is prohibitive.

I love my Olfa Ergonomic. It keeps me from cutting myself, since I have to focus to keep the blade out. I also like that it is ambidextrous, since I am left handed. The Martelli felt too awkward for me.

I agree. How did our mothers & grandmothers ever make quilts? They didn't have rotary cutters, mats, die cutters, and they still managed to make us look like amateurs!

I would stick with my Fiskar 45...would make sure I got the titanium blades

I am replacing all my Fiskars with Olfas. I just like the grip better on the Olfa and I use the 60mm and the 45mm sizes (the 60 more often than the 45). I think it's all just a matter of personal preference.

I prefer the Olfas over the Fiskers. I like all the different sizes.

You should easily be able to cut through that with a sharp blade - I do it all the time when I am cutting out strips because of how I fold my fabric, . You can, with some effort, cut through about 10 layers with a 45mm blade (and a 60mm isn't much easier), but I wouldn't suggest it if you are cutting out a lot... the repetition with that much force gets very tiring - it's much easier to make more cuts with less effort. It's more of a challenge to hold your ruler steady on a stack of 10 fabrics than to actually cut the material though.

I have a variety of rotary cutters, but I usually use the 45mm when cutting out patterns and the 60mm when I'm just doing straight lines. Unless of course I can't find one or the other (they tend to get "lost" when I pack up a project if I include any tools) then I use whatever is available to me :)