I've been in your situation a few times trying to "round out" my collection. Unfortunately for me, I have grown tired of the mundane (meaning the prices have gone up). I have guns in .22 LR, .32 ACP, 9mm, .357 magnum, .40 S&W, and .45 ACP. I also have 3 12 gauge shotguns, 2 AR-15s, and a .30-06. I have been looking at the FN 5.7 any may eventually pick one up.
My carry guns get the most use followed by my 1911s in 9mm and .45 ACP. I think I'm done collecting (for now) stuff that probably won't get shot much (if at all).
Your line of questioning for your next gun should probably be:
- What does this new gun do that the others don't?
- Would this gun be filling any specific role (HD, CCW, Competition, Range Toy, Investment)?
If you can't really find a reason for it, you should probably pass on it. Spend the money on ammo or training. Hurricane Irma was an eye opener when I was really concerned about losing my house. I have a crap ton of guns any I really only shoot about 4 or 5 of them regularly.