I don't tend to use patterns that require a specific ruler. That said, I do have a number of the "basic" rulers.
8.5 x 24.5 - my usual go to ruler for cutting fabric
6.5 x 12.5 - great for when I need to work in tight spaces, measuring lots of stuff such as strip sets, etc.
6.5 x 6.5 - great for sizing units made from strips
9.5 x 9.5 - square up ruler
15 x 15 - square up ruler
1 x 6 - very old and great for trimming folded corner units
1 x 12 - same as above but irritatingly long when doing the trimming at my sewing table
Deb Tucker Wing Clipper - for my flying geese blocks (this was my Christmas wish list item)
Gee, that's a lot of rulers but I don't have a tremendous amount of space so find that the smaller rulers get a lot of use. And I'm done buying rulers. These more than suit my needs.