Most played cards in Esper:

3 Decks
Preordain
12 copies - 4 average
Force of Will
12 copies - 4 average
Swords to Plowshares
10 copies - 3.33 average
Surgical Extraction
8 copies - 2.67 average
Flusterstorm
8 copies - 2.67 average
Underground Sea
7 copies - 2.33 average
Flooded Strand
7 copies - 2.33 average
Tundra
7 copies - 2.33 average
Force of Negation
6 copies - 2 average
Scalding Tarn
6 copies - 2 average
Snapcaster Mage
6 copies - 2 average
Spell Pierce
6 copies - 2 average
Polluted Delta
5 copies - 1.67 average
Lavinia, Azorius Renegade
5 copies - 1.67 average
Teferi, Time Raveler
4 copies - 1.33 average
Hurkyl's Recall
4 copies - 1.33 average
Dark Confidant
4 copies - 1.33 average
Inkwell Leviathan
4 copies - 1.33 average
Misty Rainforest
4 copies - 1.33 average
Treasure Cruise
3 copies - 1 average