I have the Martelli and I love it. It came in a set with a pressing mat. The turntable is on ball bearings and turns very smoothly.

Martelli all the way, they just came out with a new roundabout. I have the large and the small. They are the best, expensive, but worth it for trimming small blocks

I have 3 rotating mats and don't love any of them. I'm going to get a Martelli.
My Mathilda seems to dull blades very quickly, my Olfa is a pain to turn, and my Sue Daley is just okay.
But a rotating mat is a great tool to have. I just need the right one!

I, like a few others, am not a fan of rotating mats. I've had several and found them cumbersome. I just turn my regular mat if I need to rotate and have been doing so for years.

I think I'm at the stage where I don't want anything else unless it's going to revolutionize my quilting (except fabric of course. I always want new fabric).

I have the smaller size round one ( @8" across) with finger grooves. It works great for pieces up to 4 ". But a square one would've been better, because then l could go to maybe 6" without my ruler " falling off the edge".

I have one, but because it can move/rotate, it moves when I try to cut on it.

The large Martelli Roundabout is 16 inches which makes squaring up big blocks a breeze. I use mine for cutting fabric more then squaring up. No turning the fabric or ruler to subcut. It's one of my favorite quilting essentials.

I have an older 12 inch it is green. I do not care for it. It has a lump in the middle that is awkward. I find I turn the whole mat rather than use the rotating part. If I buy another one, I will look for a small square matt and just turn the whole thing.

I made 2 rotating mats about 7 years ago. I just used a lazy Susan and placed my small cutting mat on top. The largest one is about 15” in diameter same thing with that one as with the smaller one. The one lazy Susan was at the Salvation Army or Goodwill and the big one was gifted to me. I’m not spending crazy money on some of those mats.

I tried the lazy susan idea long ago. Just wasn't a good solution for me. I couldn't find a heavy enough lazy susan. Most were wood based and didn't turn smoothly.