Most played cards in 4C Goodstuff:

4 Decks
Disenchant
16 copies - 4 average
City of Brass
15 copies - 3.75 average
Underground Sea
15 copies - 3.75 average
Swords to Plowshares
14 copies - 3.5 average
Tundra
12 copies - 3 average
Scrubland
11 copies - 2.75 average
Blue Elemental Blast
9 copies - 2.25 average
Divine Offering
9 copies - 2.25 average
Badlands
8 copies - 2 average
Fellwar Stone
8 copies - 2 average
Lightning Bolt
8 copies - 2 average
Hypnotic Specter
8 copies - 2 average
Strip Mine
7 copies - 1.75 average
Sedge Troll
7 copies - 1.75 average
Energy Flux
5 copies - 1.25 average
Red Elemental Blast
5 copies - 1.25 average
The Abyss
4 copies - 1 average
Maze of Ith
4 copies - 1 average
Hymn to Tourach
4 copies - 1 average
Underworld Dreams
4 copies - 1 average