[Ruger45LC]

A pistol or revolver both have pros and cons. I would generally recommend a 9mm but the only two issues I have with a pistol for new users are these. One, while 9mm doesn't recoil much, any pistol can be prone to malfunction with limpwristing. Two, if it's got manual safety, are they knowledge enough with the gun to know, when under pressure, to disengage it? Point and squeeze the trigger should be all that's involved here.

A revolver isn't prone to these things, but they're bigger and heavier (usually) and have terribly low capacity. I woudn't recommend a small revolver, as small ones aren't fun or easy to shoot well, especially the really lightweight S&W J-frames. Something like a 4" GP100 would be just about perfect. However, a full on 357 Mag is very loud outside, let alone indoors.

Overall, I'd recommend something like a Glock 19 (or S&W M&P 2.0) for a pistol, no external safeties to worry about and has good capacity and low recoil. For a revolver, something like a 4" GP100 is good, loaded maybe with mid-range 357's, maybe not full magnums.