I know we had a thread about what Kingdom would require the most table space for the setup a while ago. Basically we'd be looking at most total card piles plus mats.
Of course, by having just Black Market, you can also require every single mat and non-supply card ever created for Dominion. So I think to make it an interesting question, you have to ban Black Market.
I'm sure you'd want both Page and Peasant, as those each count for 5 piles instead of the normal 1.
Young Witch
Page (4 extra piles)
Peasant (4 extra piles
Marauder (Ruins, Spoils)
Border Guard (Lantern, Horn)
Vampire (Hexes, Bats)
Druid (3 separate boon cards)
Pirate Ship
Native Village
Island
Any Reserve card
Every Landmark
Every Project
Every Event
I don't think it's possible to also use the Coffer/Villagers mat and/or the VP token mat. If you just want to use all mats you can; but it would take less table space than using the Travellers.