Most played cards in B/U Zombies:

3 Decks
Sunken Hollow
12 copies - 4 average
Cryptbreaker
12 copies - 4 average
Voldaren Pariah
12 copies - 4 average
Choked Estuary
12 copies - 4 average
Haunted Dead
12 copies - 4 average
Prized Amalgam
12 copies - 4 average
Relentless Dead
11 copies - 3.67 average
Liliana, the Last Hope
11 copies - 3.67 average
Grasp of Darkness
11 copies - 3.67 average
Distended Mindbender
11 copies - 3.67 average
Sinister Concoction
8 copies - 2.67 average
Transgress the Mind
7 copies - 2.33 average
Fleshbag Marauder
6 copies - 2 average
Clash of Wills
6 copies - 2 average
Westvale Abbey
4 copies - 1.33 average
Ultimate Price
4 copies - 1.33 average
Hangarback Walker
4 copies - 1.33 average
To the Slaughter
4 copies - 1.33 average
Jace, Vryn's Prodigy
4 copies - 1.33 average
Collective Brutality
3 copies - 1 average