I use Olfa and I use the titanium blades. I find they last longer and cut sharper.

I use a 45mm Fiskars most often but I have an old 65mm that I just bought a replacement blade for and love using. Makes quick work of cutting. I like how the Fiskars feels in my hand. I can get a 5 pack blade replacement for $13 and change from Amazon which is cheaper than buying with a coupon at Joann's.

I just got the Martelli rotary cutter and like it a lot! I got both the 60 and the 45 (long story). Before that I only used Fiskars.

I love my Martelli cutters. Curved for a more comfortable grip for me

I've been using the Fiskars 45mm for years. I like the larger grip because I do have carpal tunnel issues from time to time.

I also prefer the Fiskars, still use the first one I ever purchased back in the 80's. My hands are small and this is the most comfortable one for me.

I love my Fons and Porter rotary cutter because it automatically goes out to cut and then when you take the pressure off the mat, it goes back to safety mode. After the emergency room run and the over $600.00 bill (think how much fabric I could have bought, sigh), my husband bought this one (actually two of them) for me.

Buy one that fits your hand well. Then buy good blades. I own a 45 and a 60. I just bought titanium blades and love them.

Rotary
 

I used to get cheap ones. No more. You can get fiskars or olfa on sale or with a coupon at Joanns. They are cheaper at Michaels and AC Moore and the 50 percent coupon makes it reasonable. For no special reason I've ended up with fiskars probably because of the sale. They have a new safety cutter. It took a little getting used to but I really like it. It also closes automatically.

I prefer the Kai cutters as they retract automatically when you release the pressure on the blade and are therefore safer. I also have a Martelli which is designed for left or right handers but one still has to manually close the blade.