I have lots of rotary cutters, all brands, colors, and shapes. I have a shoe box bin full of them. In fact got a new 28mm today in a subscription box. My favorite is the Quilter's Select weighted one. It cost the most but it's a dream to use. I would buy another one if this one broke. I don't care for the 60mm size. I never have much luck using those for some reason.

I changed to the Martelli 45 cutter a long time ago. It has made a great difference in my wrist. Last year I got the 60 and was so impressed I bought 2 more!
Easier on layers of fabric but I use it only 2 to 4 layers also.

ps: I've had many brands but this is by far my favorite!

I have 3 or 4 Olfa 45's, and 1 Olfa 28. All are the straight handled ones, since I'm ambidextrous.

I have 2 Fiskars, 45 and 60, and the rest are Olfa. I have one 18 mm; one 60 mm; two 28s, one straight and one ergonomic; two straight 45s ; and at least two ergonomic 45s. One of the straight 45s is used for the pinking blades. I prefer the ergonomic to the straight. I don't like the slide lock of the regular ones. I may have more, but I think this is correct.

Leslie

I have every size they make,mostly Olfa but a Martelli and another one I can't remember the name of, maybe Fiskars. I use them all. Don't really have a favorite.

My absolute favorite are the Omnigrids. They are very comfortable and safe. Get them from Walmart online... can’t find them in LQS. Their blades work best but others fit.
Haven’t heard of Quilters Select cutters but love their cutting mats!

I have about five 45's (they keep hiding from me), so I purchase a new one. Three 60's, two 28's. All my cutting is done in locations other than my sewing room due to its size (I am lucky enough to have two sewing days a week with friends).

I have several Olfa cutters, by far my most used and favorite is the 90mm. I have a Martelli ergonomic one that I haven't tried out yet. It is a 45mm.

* I meant the 60mm, I'm pretty sure there isn't a 90!

I like the feel of the Fiskars 45, so I haven't explored most others. I don't mind having to retract the blade.

I only have one standard fiskars (45). I didn’t even think about having more than one.... Judging by these posts maybe I should!