Most played cards in R/G Control:

4 Decks
Eternal Witness
16 copies - 4 average
Birds of Paradise
16 copies - 4 average
Arc-Slogger
13 copies - 3.25 average
Stone Rain
12 copies - 3 average
Naturalize
12 copies - 3 average
Magma Jet
11 copies - 2.75 average
Molten Rain
11 copies - 2.75 average
Sakura-Tribe Elder
10 copies - 2.5 average
8 copies - 2 average
Plow Under
8 copies - 2 average
Pyroclasm
7 copies - 1.75 average
City of Brass
7 copies - 1.75 average
Solemn Simulacrum
7 copies - 1.75 average
Viridian Shaman
6 copies - 1.5 average
Chrome Mox
6 copies - 1.5 average
Kiki-Jiki, Mirror Breaker
6 copies - 1.5 average
Sowing Salt
5 copies - 1.25 average
Kodama's Reach
4 copies - 1 average
Kumano, Master Yamabushi
4 copies - 1 average
Circle of Protection: Red
4 copies - 1 average