Another vote for Creative Grids here! I'm slowly replacing most of my other rulers with CG, for me they are the easiest to read and I love that they don't slide. They're more pricey than a lot of my prior ruler purchases, but it's worth it to me to have tools that work best for me.
My favorite rotary cutter is my 60mm Olfa with the quick-change for the blade. I also have the 45mm style where it closes the blade when you let go, but I hate changing blades on that one because the little springy washer thing always tries to escape, and then I have trouble remembering which direction it goes!