I'm a ruler/template junkie. I have more of the Creative Grids than anything else, but seriously LOVE the Loc-bloc for triming my blocks down accurately. I also have two of the Quilters Select rulers but very seldom grab for them. There are also some Missouri Star rulers/templates in my holders. Not afraid to buy a new one even if it's something that will only get used once a year.
Make a list of all the rulers/templates you really want, and from there figure out which ones you would get the most use from.