I have been playing since it was in beta. I am rank 8 and I hover between 1600-1700 and have some decent cards leveled up to 8 for commons, all 4 or above for rare, and all at 2 for epic. I am 100% f2p.
The one thing I hate the most is lightning towers because everyone is using them now, they are just a mini tower to distract your cards. You absolutely have to have a counter for it and no one car should dominate the meta that much.