We had Mythic Dungeon Invitational and Tespa Collegiate Dungeon Race is currently ongoing, but I just wanted to highlight some differences between the two formats and see poster's thoughts on M+ as spectator sport and which format they liked better.
MDI - Access to all Legion gear at 935 ilevel, 965 weapons +17 keys.
Tespa - It's uncertain what ilvl the players are at, but it's apparent that all the participants are using characters copied from live.
I'm not sure if there is an ilvl cap for Tespa, however it's very aware that the players weren't given access to the same gear and power-gaming strategies as MDI. Notably because healers don't all have 935 Umbral Moonglaives to use, and players seem limited in their Legendary collection compared to what they had on live.
For me, I am finding Tespa more entertaining, in 2 days we've seen several tanks, healers, and dps represented. The gear availability is lower so the keys are lower. +14 seems easy when teams are doing +20s, but in this case they're not just doing the dungeon in time, they're racing against the other team, pushing teams to commit to far riskier strategies.
The requirement to using live characters seems to me like a better direction for the format, as the MDI format often meant every team minmaxed the theoretical 'best tank/dps/healer for each dungeon. For me it's far more entertaining seeing many classes and specs represented than just Bear/Resto Druid/Sub Rogue/Arms Warrior every run.