I would say my GC defining favorite event is any time that something besides pure watts wins it, such as Contador's Fuente De. Any kind of skills, tactical coup or creative teamwork (NOT a mountain train) which overcomes a deficiency of straight horsepower is what I'm rooting for. Better to be like Nibali than Froome.
a long range attack (sometimes), an ITT, or simply dropping the hammer on the final climb are all different forms of having the biggest engine.
to a certain extent, this guarantees I am always rooting for the underdog, because the favorite will rarely be forced to get creative.