Another vote for the Ultra-Dot. They are available in fixed and variable dot sizes (I like 4 inch), a little less $$ then the Fastfire. They are as small as a tube type sight gets, and are very durable. I have tried to kill mine, mounted on a Ruger .44 mag, for years with no success. The Fastfire is also a good choice for a small, relatively inexpensive but durable holo type sight. I have several of those on guns with some recoil, also without issue.
Larry