I have an older Olfa (both 60 & 45) and have always been happy with their performance, as long as I remember to close the blade....

I replaced my Olfa 45mm with the quick change Olfa. I love it. I absolutely hated changing blades before and put it off as long as possible. The quick change is just that - quick!
http://www.olfa.com/rotarycuttersdet...px?c=81&id=520

I have never used anything but an Olfa rotary cutter, and I love them. I am sure there are other good brands out there, but I have not tried them.

A have a small Olfa, two medium Olfas, one large Olfa, a medium Fiskars, one medium Martelli, and one large Martelli... There is no contest... because of my carpel tunnel, the Martelli cutters enable me to cut more fabric without pain. I don't like the Olfas. The Fiskars is good, but not ergonomic like the Martellis.

I have several cutters. The best one for me is the Gingher cutter. It is solid and easy to glide down the edge of a ruler. I have more success with this cutter than any other cutter.

Where can I find the Martelli cutter

Me too! Even though I do have a few other kinds and switch them back and forth. The Martelli blades are great though and can really cut thru a lot of thicknesses.

I have abunch of cutters but my favorite is the omnigrid 45. It opens with pressure on the mat and closes with release of pressure. No chance of an accident! The only drawback is it does not work well on a shapecut so thats the only time I use an olfa.

Martelli is out of Florida. Google it ! ! ! They are wonderful and gaurenteed. A little pricey but well worth it.

I love my Gingher as well, and I use any blade I can find in it, including ones from Harbor Freight!