The problem comes about in that,
if Tesla's theories are correct, then Einstein's theories are wrong.
And since Tesla built all kinds of actual devices, and Einstein built nothing (except maybe an atomic bomb) I stand with Tesla. Also, all of his theories work out, and Einstein's do not. Well, at least he popularized that space could be curved.

Spooky action at a distance happens. Communication across the universe can happen almost instantly. The galaxy spins as if all the stars were glued to a plate, so gravity is not what operates the galaxy. Etc.

And there are further indicators that show that Einstein was a puppet set up to take all of the fame and attention away from the real geniuses.