USAC is the home of most of the high-level competitive trainers and tournament organizers, and quite a bit of amiibo research goes on here! If you’re experienced in the amiibo scene, or you want to level up your knowledge, USAC is the place to go. (But if you’re new, keep scrolling!)
SUAL is the best place to go for that “Smash weekly tournament” vibe. Every Sunday, SUAL hosts an arena tournament, and they’re really great to watch! I tune in whenever I can.