I have to say I agree with Jimmy above
I tend to use both - but at times it depends a bit on the mood that I'm in. Yahoo answers - in some of its sections at least has become a bit like a political talking shop. There also seem to be some users whose only aim is to trade small talk with each other or to trade insults with others.
Yedda is "cleaner" and "slicker" and more enjoyable.
Well done to the Yedi (collective noun for all those in Yedda) for providing a great resource