Peasant Tribal Cube
Here's my cube! Observe it's archetypes:
WU Fliers (Control)
WB Clerics
WR Warriors (Equipment)
WG Tokens
UB Rogues (Mill)
UR Wizards (Spells)
UG Merfolk (Midrange)
BR Goblins (Aggro/Sacrifice)
BG +1/+1 Counters
RG Elementals (Landfall)
Black and red both sacrifice heavily, and changelings unite the cube. You'll note some one-off tribal effects, and those are there for changeling shenanigans!
The cubes tribes exist primarily in their own colors, but there is some bleed you may feel inclined to splash for. Personally, I'm fond of decks that combine two tribes effects with changelings, such as a RB Elemental Goblin deck. I like to think that the tribes mechanical identities, along with the inclusion of changelings and ample cross-pollination make this cube not so linear, as tribal cubes tend to be.