I have a 12 inch metal ruler that the markings are so small I can't even see the marking on it with glasses on!

The best ruler I have ever purchases is a 18" X 6 with adjustable locking fabric Guide made by Westalee design. It has 2 screws that you adjust the wide you want, then put it next to the fabric to be cut and it holds it in place.
One that I have never use is a dresden, but then I have never made a dresden plate yet, so it may come in handy someday.
Also, I use a hand on all my rulers that can be purchases at quilt shops or in the bath supply dept. That helps hold the ruler in place, keeps finger away from the cutting area. It's worth every penny.

Just discovered the foam sheets with adhesive backing, cut 1/4 inch squares and put on the back and the ruler does not move.

I have that one, I use it on the frame; put it under the clamp when it saggs. LOL

I bought 2 rulers that have the 1/4" lip on one end. I don't think that they will be accurate enough for me so I never use them.

I have a Lazy Angle ruler that I have never used, but a neighbor did borrow it once!

I have a couple of triangles that I don't use, but you never know. I don't think you can have too many rulers. I used a right angle triangle for a quilt recently, and I was glad to have it. I do a lot of paper-piecing and I love the Add-a-quarter and Add-an-eighth rulers. I wouldn't want to paper piece without them.

I love my EB flying geese rulers--I have 4 sizes. I'm going to make a star quilt this fall and that's what I'll use to make the points. I've got F&P one and don't care for that one. I find EB's method quicker and better than anything else I've seen.

I have rulers I have never used so I don't know if they were a waste buy or not. If a ruler is on clearance below 1/2 price, I buy it. I have one that is only for 7/8" measurements. From 1 7/8" to 6 7/8". I use it more then I thought I would.

I'm a 'gadgeteer'! When a new ruler comes out (or anything else), I buy it. I have a Salem folding ruler - useless. I have many triangle rulers I don't use. I purchased the Hunter's Star ruler and plan to use it - someday. My favorites are 6x12, 6 1/2" square. Could get by just fine with these.