Recommended HD gun....
I'm relatively new to the hand gun shooting sports, as are you. I've owned a pair of Springfield Armory polymer pistols for 2+ years - ever since getting my concealed carry permit (add this to your 'to-dos'). One is a .45 ACP Compact, 5" barrel, with a few extra higher capacity 13 rd magazines. The other is a Compact 9mm, also with hi-cap mags.
I love them. No failures, comfortable, ambidextrous, shoot straighter than I can, priced right for range and HD use, good plinkers, they passed the Glock 'torture test' better than the Glocks, and will carry concealed... (kinda' sorta', I'm a wide-body craft and can hide Roscoe fairly well with the short or long mag).
Just my preference, though. You will get LOTS of good recommendations. Shoot all you can. Even the .45 isn't too expensive. I bought a slug of ball and HP ammo at a gun show, got set up to reload. Try it - it's therapeutic!
"Figure Out What You Believe and STAND YOUR GROUND!"
Nemo Me Impune Lacessit
Lots of Cast Iron to Cook With...
and a few defensive firearms, too!