Assuming you meant most lucrative, are Junior, Amateur, and/or Masters more lucrative? Why?
From a TD/organizer perspective, pro events are definitely the least lucrative and therefore the least attractive to run. With amateur tournaments, the profit margins on player pack and prize merchandise afford organizers the opportunity to cover most if not all their costs, perhaps even have something left over at the end. There is no such margin to draw from at pro events, so you're immediately in the hole. Obviously you seek sponsorship to help with this, but it's less of an uphill battle to break even with amateurs.