Good graph from this 2011 article:
This is a tough call, but honestly, WebM is probably going to win out in the end considering it’s Google’s project. Ogg will most likely stay what it is now in its audio counterpart– an open standard that is not widely-adopted even though it’s superior in some ways.
H.264 is Apple’s, WebM is Google’s. Apple will most likely end up adopting WebM, and Google will most likely continue to pare back H.264 on their devices.
I’d base your decision more on longevity than on video quality, the reason being that the quality isn’t that different, and even better quality could end up losing in the end. Remember Betamax?