Most played cards in 4 Color Control:

2 Decks
Brainstorm
4 copies - 2 average
Prismatic Ending
4 copies - 2 average
Ponder
4 copies - 2 average
Force of Will
4 copies - 2 average
Misty Rainforest
4 copies - 2 average
Swords to Plowshares
4 copies - 2 average
Flooded Strand
4 copies - 2 average
Uro, Titan of Nature's Wrath
3 copies - 1.5 average
Pyroblast
3 copies - 1.5 average
Minsc & Boo, Timeless Heroes
3 copies - 1.5 average
Endurance
3 copies - 1.5 average
Carpet of Flowers
3 copies - 1.5 average
Dress Down
2 copies - 1 average
Life from the Loam
2 copies - 1 average
Terminus
2 copies - 1 average
Force of Vigor
2 copies - 1 average
Blue Elemental Blast
2 copies - 1 average
Force of Negation
2 copies - 1 average
Narset, Parter of Veils
2 copies - 1 average
Tundra
2 copies - 1 average