I have 3 that get very regular use: a 3.5 inch by 24 inch oldie that I bought in 1986. I love it because it's long enough to cut across a folded length of yardage. The 3.5 inch width is enough to give me a lot of options for most of the strip widths I'd want to cut. I love it so much the numbers are getting a little faint in places, which makes me sad, since I don't see these rulers around anymore.
What really amazes me about this question if the fact that you remember purchasing a ruler in 1986. For me, if it wasn't yesterday, forget it. I just have it. LOL