This is a tricky one. The volume of posts in reddit is overwhelming, and 99% is shitpost / memes and such. I haven't looked for anyone in particular to follow, but from time to time there are good posts. Check, according to your interest
https://www.reddit.com/r/algotrading
https://www.reddit.com/r/options
https://www.reddit.com/r/smallstreetbets
https://www.reddit.com/r/thetagang (retards posting very seriously)
https://www.reddit.com/r/thewallstreet (probably relatively most sane)
https://www.reddit.com/r/wallstreetbets (retards posting as retards)
Meet us real time retards here (don't expect anything of value): https://discord.gg/wallstreetbets
Edit: In reddit trading discussions, retard is term of endearment. That should be clear
I forget how /options is. /futures is eh