I've explored countless sites and have a few favorites that stand out. 'Archive of Our Own' (AO3) is my top pick because of its massive library and excellent tagging system, making it easy to find exactly what you're looking for. The community is also super supportive, and the quality of writing is consistently high. Another gem is 'Wattpad', which has a ton of BL stories ranging from fluffy romances to dark, angsty tales. The interface is user-friendly, and you can interact with authors directly, which is a huge plus.
For those who prefer older, more established platforms, 'FanFiction.net' still has a decent selection of BL works, though it's not as organized as AO3. If you're into Asian BL fanfiction, 'AsianFanfics' is a must-visit, with a focus on K-pop, anime, and drama fandoms. Lastly, 'SquidgeWorld' is a lesser-known but fantastic site with a lot of niche content. Each of these sites offers something unique, so I recommend checking them all out to see which one fits your preferences best.