Yahoo Answers is bigger and gets more questions and answers. I think Yedda has better quality
If you are a dedicated marketer, better id you use both YEDDA and YAHOO ANSWERS. Both these Web 2.0 sites are fun, easy-to-use, and can help generate leads in the long run. YAHOO ANSWERS has already build a huge name on their own but it doesn't mean you simply ignore the young YEDDA.
Yahoo answers is just full of spam and silly answers which don't answer the question :-)
Yedda is more easy to use, its new and a lot of Genius are here to answer your questions very rapidly as far yahoo answer is considered its full of spams these days.
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them