I like the rulers that are marked with yellow and black. I find them easier to align. My favorite sizes are the 6x12 and the 6 1/2 square. However, I also use the 15 square and the 6 x 24 for squaring the top, and I recently bought some more squares for my blocks. (9 1/2 and 12 1/2).
The triangle rulers I bought were a waste of money (for the mose part). I generally use the angle line on the 6 x 12 ruler to do my angled cuts.