I also don't think there's a 'best' rotary cutter, however, the shape of the handle varies widely. You need to get one that feels good in your hand and causes the least amount of stress. I have an ergonomic Martelli cutter, and I also have a KAI that I bought in the 90's (80's???). Alternating these two seems to cause the least amount of cutting fatigue. Both of these have thin handles. When one brand of cutter came out with the thicker handle, I got one and it just didn't fit my hand, so I gave it away. If you have any quilty friends, I would ask to use their cutters and see which one you like best. I use a 45MM for most cutting, but I do have a 60MM for trimming quilt sandwiches. Never seemed to need the tiny one. If I need something that small I use scissors.