Well, the point of a new tournament format as I see it would be to get unusual match-ups played without interfering with actual gameplay.
For that, I think 19XX, Pick Your Poison and the Balanced Clash are the gold standard. Honorable mentions to LLL. (Random select is very varied and very hype but sometimes quite feelbad.) Stables tournaments like the Yomi Olympics can also be fun but they basically punish you for not playing top tiers IMO. Points based stables could address that but then you have a cost balance issue. The idea of Lum’s Long Odds was good but I think I’d have to say it didn’t work out so well in practice, the counterpicking issue and Swiss format were very anti-hype. Maybe with some refinement it could be brought back?
I like the idea of the Take This Challenge.
In a similar vein, what about something like
ROUND AND ROUND IT GOES
Full cast Bo7 mid timer, first game double blind, both players switch after each game, but winner switches first, not blind, and loser can then counterpick their choice. Neither player can pick any character that they’ve already played in the same set. (You can’t stay on the same character or go back to one you’ve already used.)