Most played cards in Esper:

35 Decks
Force of Will
140 copies - 4 average
Flusterstorm
124 copies - 3.54 average
Hurkyl's Recall
105 copies - 3 average
Urza's Saga
89 copies - 2.54 average
Swords to Plowshares
87 copies - 2.49 average
Tundra
78 copies - 2.23 average
Underground Sea
67 copies - 1.91 average
Paradoxical Outcome
57 copies - 1.63 average
Pithing Needle
53 copies - 1.51 average
Polluted Delta
52 copies - 1.49 average
Misty Rainforest
49 copies - 1.4 average
Flooded Strand
46 copies - 1.31 average
Scalding Tarn
46 copies - 1.31 average
Lavinia, Azorius Renegade
46 copies - 1.31 average
Sensei's Divining Top
45 copies - 1.29 average
Preordain
43 copies - 1.23 average
Mox Opal
42 copies - 1.2 average
Leyline of the Void
38 copies - 1.09 average
Soul-Guide Lantern
36 copies - 1.03 average
Mox Pearl
35 copies - 1 average