If it was me I would get the Olfa Deluxe Rotary Cutter which is ergonomic.
I have the 45mm and it fits very well in my hand. You'll have to try and
see which one fits best in your hand. What fits mine might not necessarily
fit yours. It's like shoes.
Doesn't matter what rotary cutter you get, you still have to take breaks.
I find that the Slidelock ruler really helps my carpal tunnel. I don't have
to put as much pressure on my hands. I don't even use the wrist brace
anymore but I do take lots of breaks.