I like Omnigrid rulers - most of them anyway. Mine have yellow or green highlights on the inch lines. I have one 4.5" square I don't like to use often because it has too many lines. It's got lines at the 1/8 increments, not just short lines at the cross lines, but full lines across both directions. It's distracting and I have to mark my spot with a post-it so I don't use the wrong line.
I like the 6x24 for cutting borders, but don't like it for general use because it's too big. I use my 6x14 or 4x14 most often. I use the 9.5" and 12.5" rulers for squaring up. I love my June Tailor Shape Cut ruler and use it frequently for strips. I like having different angle lines on them (just in case).
I doubt I could ever find one ruler that does it all that I'd be happy with. I like to use the smallest ruler possible for the project I'm working on.