I've tried a few versions of D&D, briefly played Pathfinder once, did quite a bit of Scion, also some Apocalypse World and Dungeon World for some things that didn't last long, and recently started a campaign using the FATE system.
That FATE one is a thing my brother is doing and I'm hilariously overpowered in it without even trying to be, largely because the system is a little silly and my brother is rather crap at homebrewing. The FATE system doesn't have attributes like strength and whatnot, just a bunch of skills with some modifiers attached to them. He decided he wanted to do custom magic schools to go with the world he made. It's an evil campaign, so I took the dark magic skill as my best thing. He decided to make it so classes of magic give specific spells rather than keeping it vague like the base game is for other combat skills. One path of dark magic is manipulation stuff where you can literally mind control people, and if you do well enough you can permanently make them your mind slave... as a level 3 spell in a system that only goes to level 10. He wanted to railroad my character into getting captured by some paladins, but I managed to hide from their shitty perception skills (all 7 of them rolled just okay or poorly versus my great stealth roll) and also mind controlled their leader to make them go away. The railroading ensued anyway, but in our little prison escape I've already made one paladin my mind slave and because he didn't put any limit on it I intend to attain an army of chumps to become a true evil overlord. I would feel bad about abusing his poor choices for magic, but I warned him early on and he said it was fine and he knew what he was doing, so now I can't wait to be able to throw dozens of guys at a boss fight. :3
I'm also DMing a campaign in D&D 5e, which I made as a thing with some very specific end goals rather than just an open "go do things" campaign. I've found that planning out only the sort of main plot in great details, then only broad brush strokes for everything else and just improvising anything else needed is the most fun for me. Instead of spending hours and hours working out details, I can prepare for a 5+ hour session in about 2 hours and end up with nigh infinite flexibility to allow players to do whatever the fuck they like.