Creative Grids for the thin lines and no-slip feature and June Taylor Shape Cut. I have 25 kajillion rulers and I find myself reaching for the June Taylor every time I cut strips for a project. I can have 6-8 strips cut in less than 30 seconds and all are perfectly accurate. Take a look on You Tube for the June Taylor videos. That's what convinced me.
However, I like having the ruler I need for the job I'm doing. Sometimes, I need a very small, maybe 3" square for working while at the machine. Sometimes, I need a 24" square for block squaring. I even bought one that unfolds into a large right angle and have used it several times to square up quilt corners. But June Taylor is the most used.