For my first few quilts I got by just fine with my 12.5 square, a 6.5 square, and a 6 x 18 rectangle that I stole out of my mother's stash. I have acquired a handful of other rulers since then, but those three are still the ones I reach for the most. As for specialty rulers? The two I use the most are a flying geese ruler, and one specializing in cutting triangles for HST by the finished size. Takes the pain out of cutting fabric by the eighth of an inch and saves fabric in the long run. Every other ruler I have I purchased for a specific purpose and haven't touched since that project was completed. Now if they tell me I need a specialty ruler and I can't figure out how to do it without one, I find another project.