It is kind of a matter of perspective IMHO. Depends on what sanctioning body you compete in and what you consider "respectable".
KCBS = AR Invite AND the Jack, and now Samís Club Finals
MIM/MBN = Memphis In May
Between these comps, the largest is MIM, but if you include AR Open then that is the largest.
Most respectable/prestigious "Whole Hog Cook-off" would be the Newport Pig Cooking Contest (80 to 100 teams cooking ONLY whole hog on the grill).
But you canít leave out the World Barbecue Championship as part of the World Food Championship in Las Vegas or the World Barbecue Championship sponsored by the World Barbecue Association (even though there arenít many (if any) teams from the USA involved).
CMJ - KCBS (100+ club) & Carolina BBQ League (NCBBQA)
CBJ - MBN, NCBS, NCPC, SBN
CTC - KCBS
4 Lil' Pigs Competition BBQ Team
LANG, BDS, & Holland