i have installed ubuntu and apache and other crap to have a real server instead of some windows 10 crap, but one question, what should i put on there and should i buy a domain or use cloudflare's crappy subdomains

well, domains can be pretty pricey especially when youre like me dont have all too much money and/or get money infrequently. it depends on whether or not you think you will use it enough for it to be worth it.

also dont be hating on windows, it can still be a real server!!!