The quantum gravity community alone has a whole plethora of competing, mutually contradicting theories even within subgroups like string theory. Well-known and respected physicists make their careers off of proposals like:

  - Two time dimensions [1]
  - Reality is actually a discrete, combinatorial graph [2]
  - We live in a Euclidean space virtual machine on a 
    general relativistic virtual machine on a Euclidean actual machine [3]
  - Reality is a souped up version of liquid helium, 
    and of course dark energy is just surface tension [4]

I took a bit of license with these descriptions, but when this stuff doesn't get you written off as a crackpot (as long as you've got an actually theory going on and can explain it to others), what will?

[1]: http://physics.usc.edu/~bars/twoTph.htm [2]: https://en.wikipedia.org/wiki/Loop_quantum_gravity [3]: https://en.wikipedia.org/wiki/Euclidean_quantum_gravity [4]: https://en.wikipedia.org/wiki/Superfluid_vacuum_theory