I have sworn off crush washers and peel washers for muzzle device alignment. It is too easy to over-torque crush washers and peel washers are a pain to deal with. Shims are, by far, the best solution. They are easy to use and help ensure your muzzle device is as close to straight as possible (which is why they are a must for suppressor mounts). The only problems are that shim sets tend to cost more than crush/peel washers and that they are hard to find for some thread patterns. That is why I was glad to come across Griffin Shim Sets.
I have paid $12-15 for shim sets before but Griffin Armament’s are $6.99. That is still more expensive than a crush washer but you will save money in the long run because it is often possible to mount more than one device with a single shim set and the shims, unlike crush washers, can be reused. On top of that, they are available for 4 different thread patterns.
Check out the Griffin Shim Sets at Griffin Armament.