IBJJF
Gi and no-gi, belt-ranked, age and weight divisions.
Best for: intermediate to advanced competitors.
ADCC
No-gi focus, with Opens for regular competitors and Trials and Worlds at the top.
Best for: novices at an Open, elite competitors at Trials and Worlds.
AJP Tour
Abu Dhabi Jiu-Jitsu Pro Tour, gi and no-gi, international circuit.
Best for: intermediate to pro.
NAGA
Skill-level divisions (Novice, Beginner, Intermediate, Expert), gi and no-gi.
Best for: first tournaments.
Grappling Industries
Round-robin format, several matches per entry.
Best for: novice to intermediate.
Fuji BJJ
Belt-based gi, skill-level no-gi.
Best for: novice to intermediate.
Most of these organizers list their events and take registration through Smoothcomp. Search the organizer there for current dates and entry costs. Smoothcomp event search. Ask your coach which local events run well.