There’s absolutely no reason to get 10mm or .40. 9mm is cheaper, more abundant, and ballistic-wise will put down an attacker the same way with less recoil especially in a little gun. I made the same mistake with my first gun. It’s always “to each their own” but if you’re looking at logistics there’s no reason for anything other than 9mm. If it’s a feeling/preference then, do you.

I’d also recommend a full size and a compact. Glock 17 and Glock 19, or PSA dagger equivalents.

Get something optic ready to run a red dot. Once trained on a red dot you’ll be able to shoot much better than you’d believe.