I am really partial to the Martelli ergonomic rotary cutters.....If you can wait until they have them on their Redline Direct sales, they are 50% off - making the cost about $12 or $13...........I love their blades too......last so much longer than any others and stay really sharp..
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I love my fiskar and the titanium blades

I like Olfa rotary cutters. Only problem I have is the order of replacing the blades - even when I have laid all the parts in order. Just me.

I have several different rotary cutter bu different manufacturers. I use them all at one time or another but my go to is my Olfa 45 mm, also.
The main reason I wanted to post on here is that I recently did something I wish I had done about 4 yrs. ago. I have 4 grandbabies whom I love more than I can ever explain. I bought a plastic storage container @ JAF that you can put a lock on. So I gathered up all my rotary cutters & put them in the box & locked it up. I have always had a fear that one of my DGC would some how (I always keep them put up in a high place) get ahold of one of them. 2 of my DGB live close & are at our home frequently.
So I thought I would share this idea with others who may have children or GC, who could potentially get ahold of them. I would be crushed if any of mine got hurt because of my carelessness. BETTER SAFE THAN SORRY!!!

I love my Gingher rotary cutter. I have had it 7+ yrs and it is by far the best. I have Olfa, Friskers & the Ergo thing..One I use with decorative blades, one is for paper & the Ergo is just kinda 'in case of'. My son gave me the Gingher cutter for Mother's Day and I absolutely love it. I usually use Titanium blades when I can get them. The Friskers blades work very well in it too. The Gingher is pricey, but in my opinion, it is so worth it..

I love the Martelli ergonomic rotary cutter. I have used this for years and it's the only one I can comfortably cut with. Their blades can be a little bit pricey, but they last for quite a while.

As with sewing machines, the "best" rotary cutter is purely subjective. That said, I like the Olfa 28 mm best (this is the straight one with the slide closure). I find the 45 mm and 60 mm to cumbersome to use and the 18 mm is too small. JMHO...

I use the Olfa 45 mm cutter. Be careful. I had one explode on me and the blade actually broke in two pieces and the cutter came apart. I came apart and cut my cutting hand. Just make sure the screw is tighten each time you use it.

I've only ever tried Olfa and the TruCut.

Hated the TruCut (didn't like the hand positioning), so kept with the Olfa, which is what I started off with - it's a 45mm with manual retraction. I think size-wise a 45mm is probably the best to start with, though I like the idea of a self-retracting blade (haven't actually tried one).

If you like the handle/feel of the cutter you have you could just try swapping out the blade for a different brand - I've tried various different cheapy brands, but always came back to the Olfa ones so that it what I'm sticking with