Schill93

I really like using my accuquilt for half sq. triangles and quarter sq. triangles. When you spray starch your fabric and load it in the right direction, they are very precise. Also the cut off dog ears create a nice blunted starting sew line for you instead of having to deal with pointed fabric ends. In some cases, like in doing multiple 2 1/2" half square triangles, it is a god send, as they have a die that makes 6 triangle squares at a time, and I always lay 4 pieces of fabric on in a pass,, I get 24 HST in a single pass.

I know we were talking rulers, but I thought I would inject that as well, as what we are aiming for is accuracy in the end.
Also, I should note when it comes to squaring up larger squares (over 6") I like using the perfect size square ruler as well.
But would like to mention that I find doing so with small size rulers is much more difficult as there tendency to move is much greater the smaller they are. If you still want to do this with one of the smaller sizes, then I would get sandpaper type of tape and put it on designated square rulers used just for the purpose of squaring up. Just buying a cheap set of square sizes with the sandpaper tape will serve you well, and your fabric is guaranteed not to move.

One other consideration is the mat your using. The surface material used on a mat is a big factor in the fabric not moving on the board as well. I several different mats, but the Olfa is the winner when it comes to grabbing the fabric and not letting it slip. If you don't have one, I would get their 12" x 18" one. They are a reasonable price and good for squaring up a lot of block sizes.