I've been cruising through Bakudeku fic archives for years, and honestly, the platform quality really depends on what era of the ship you're hunting for. If you want the massive, polished, often multi-chapter epics, Archive of Our Own is the undeniable king. The tagging system is a lifesaver for filtering tropes—'Enemies to Lovers,' 'Canon Divergence,' 'Quirkless Izuku'—and the quality tends to be higher because writers can really build out their stories. I've found some absolute masterpieces there that have lived in my head rent-free. That said, the sheer volume means you need to wade through a lot to find the gems, and sometimes the 'classics' from five years ago get buried.
For a totally different vibe, I'd point you toward specific Discord servers or Tumblr blogs. The fandom on Tumblr is incredibly alive for Bakudeku; writers will post drabbles, headcanons, and short, intense one-shots that you just don't find elsewhere. It feels more immediate and connected to the current pulse of the fandom. The downside is discoverability—it's a mess unless you're already deep in the right circles. I stumbled onto this one writer who only posted 500-word angst pieces on their Tumblr, and they ruined me for every other portrayal of their dynamic. You won't get the structured reading experience of AO3, but you'll find raw, passionate stuff that often feels closer to the characters' chaotic energy.
I'd be remiss not to mention fanfiction.net, which is like digging in an archaeological site. Some of the foundational, iconic Bakudeku fics are still hosted there, written before the ship had its current name or even before Katsuki's character got the depth he has now. The interface is clunky, and you'll deal with ads, but there's a certain charm to reading those older stories and seeing how the fanon interpretation has evolved. Just don't go there expecting the latest tropes or the most polished prose.