In polymer guns, you will find far, far more accessories for Glocks than anything else, because of its longevity and tremendous popularity. The XD is probably second.
Tinkering with range toys is one thing, but I am of the opinion that defense guns should generally be left as close to stock as possible. As Cooper said, "Sights you can see, a trigger you can use, and a dehorning job."
So endeth the unrequested sermon.