My highlander cube. Started as a bulk cube inspired by some stuff LoadingReadyRun did, and after years of tweaking it's becoming something that's got a decent power level.

Archetypes: Mardu(WBR) Warriors, Naya(WRG) Go Wide, Temur(RUG) Elementals/Landfall, Esper(WUB) Fliers, Jeskai(WUR) Wizards/Spells Matter, Abzan(WBG) Counters, Grixis(UBR) Zombie/Reanimate, Sultai(BUG) Self-Mill/Reanimate, Bant(WUG) Auras/Voltron, Jund(BRG) Aristocrats/Reanimate.

Ideally, Draft with 30 card packs and take 2 cards each pick. Make a 100 card deck out of your 90 card pool. Mulligans are a little different, because its 100 card singleton drafted decks and don't want bad feels.
Mulligans: Starting 7, First mull 7, Second mull 6, Third mull 6, Fourth mull 5, etc.