For the longest time I have been having problems with Apple mail.
Any other good email programs out there? I tried Dropbox's Mailbox but that's in beta and I don't really like how it works (they have an idea that you should delete emails from your inbox as soon as you're done with them, but that's not what I do). Thunderbird... ehh... too old-fashioned. Maybe I should just use Gmail webmail and use their notifications app thing. Idk.
It really sucks that this apple mail sucks because I like the interface of it and all but it is just so glitch and buggy and it just... UGHH!!
I'm trying out different email clients. Opera Mail looks interesting.
Never had a problem with Apple mail and I use it very extensively - although I don't use it with Gmail accounts which have traditionally been a pain point for people due to Google's loose implementation of the IMAP protocol in the past (not sure if that's improved recently or not). It sounds like you're using Gmail here, which may be the root of your problems (not that you shouldn't be using Gmail - just that it and Mail.app haven't always gotten along well).
I do like to tinker with mail apps though and have tried more than a few. Airmail is pretty but buggy. Spark by Readdle is available for macOS now and is pretty nice but lacks a lot of standard features. Thunderbird is often recommended but its built-in search functionality is poor compared to what Mail.app offers.
If Thunderbird is too old fashioned for you, you might want to look at Postbox - it's based on Thunderbird, but with a much updated UI and it plays very nice with Gmail. It's not free, but there's a free trial and it's generally highly regarded. They've also improved the search abilities in Postbox. Not quite Mail.app level but close.
https://www.postbox-inc.com