i really like my rulers, though I'm still learning with them. I started with a pack of four from Quilters Rule, plus a "captured foot rope" which is really cool for making rope-design in borders. I added a couple of arc rulers, as I wanted to play with curved cross hatching. I made a quilt with medium size patches of solid color, and used it to practice FMQ and ruler work (pattern was Elvira from GE Designs.)
I second the idea of having a good grippy surface on your ruler! I think it is the most important part of using them. Some sticky stick-on dots came with my first rulers, but now I'm using Odif Grippy spray and like it better. I saw someone use hot glue thinly applied to the under-surface of the ruler and I want to try that on one just to see if it lasts longer than the spray or dots.