Who is correct is an article of faith. But both theories are complex and no experiment today can prove either correct. If you stake your entire career on either it is quite depressing if you find yourself on the wrong side of the experimental evidence. In science there is this idea known as the Occam's Razor ....the best solutions or explanation to a phenomena is the simplest one that can explain all observations - the simplest theory is likely to be the one that is correct.
"Surfer dude stuns physicists with the Theory of Everything" - Daily Telegraph
In Nov 2007, a little known physicist Antony Garrett Lisi put out a pre-preprint of a paper entitled "An Exceptionally Simple Theory of Everything". The paper initially received accolades and plenty of criticism....but became largely ignored by most physicists. There are thousands of papers written on String Theory and these would be invalidated if Lisi's simple theory turns out to be true. We will find out in a few months as the LHC generates more results. Lisi's theory predicts 22 new particles. The String Theory proponents believe that some results from the LHC showing the disappearance of energy into another dimension can help to support their theory.