My analysis as a Light Side supporter:
First, let's talk combat. A Light Side user vs. a Dark Side user. The DS user started it off with his offensive Force powers. But the LS user used his defensive abilities to lessen the effect, and used healing to make it as if the DS user had done nothing at all, if not wear them both out a little. Therefore, we'll say that for combat, they're even.
Let's talk Anakin. The only reason that he turned DS was having all that power. The Emperor tempted him, he wanted to save Padme's life, he had LOADS of Force power. and the Jedi didn't know so they couldn't ensure that he stayed on the right path.