This is a very personal question and you'll get a ton of different answers, and the right answer is what works for you. What works for one person might not work for others, etc. I used to carry a S&W Shield. Still have it but don't really carry it anymore unless I want something really concealable. Have plenty of other pistols including 1911's, Berettas, other Glocks, S&W Revolvers, CZ's, etc. But these days I carry a plain 'ole, unmodified and un-messed with, bone stock (aside from he added optic) Gen3 Glock 19 in a Tier1 appendix holster with a spare mag. Works great for me, is super comfortable, but may not work for you. Even when renovating my place and working outside in the yard or on the tractor I usually have it on me. Comfortable enough to wear all day and not cause any problems. Have been running this set-up for the last two years with no complaints.
It looks big and cumbersome, but you'd be surprised how comfortable it is, and having the spare mag is something everyone should have on them but many I know don't. I don't carry it for the extra capacity, but if yoou have a situation where the mag in the gun takes a crap on you, baseplate falls out and you lose all your rounds, have a stoppage, etc.
Small pistols just suck. Great to carry but garbage when it comes to actually using, comfort in hand, accuracy, capacity and are no fun to shoot. Big guns are great, but heavy, and as awesome as 1911's are (I love mine) they just can't compete with pistols that are similar in size but lighter with way more capacity. For a carry gun I want it to be first and foremost reliable, then affordable, super simple to run and easy to replace. Not going to carry some super expensive piece that will get confiscated if I every am involved in a self-defense situation where I had to use it and probably need see i again. Also never understood the extended mag thing. By the time you add the extended mags you might as well just step up to a compact instead of running a subcompact with an extended mag.
For classes I have a pair of identical G17's that I'll travel with. Try to keep it simple and if one goes down (never had that happen) I can easily pick up the spare and keep going in class. Have a buddy who always likes to bring different stuff to classes and he's always adjusting or tweaking stuff, and I swear he misses out on a lot of stuff they're teaching because of all the fiddling he's doing. I've shot all my pistols in classes I've taken and just decided the Glock is the way to go for me. Easiest to run, no sharp edges, parts are cheap and easy to get and replace when they wear out, and those guns will run forever. These days my nicer pistols are there just to have or to have fun with at the range now and then.
Again, this is what works for me and my body type, and can wear this with jeans and a t-shirt, but might not work for you.