I use neither, never saw the usefulness of computer chatting. I also don't trust the confidentiality of Skype anymore since Microsoft bought it.
Always going to be Skype for me, I've never liked Yahoo Messenger but fell in love with Skype as soon as I downloaded in a year or two ago. So simple, fast, and very very easy to use. I love it already!
I use yahoo Messenger and Skype.The Skype is the best for calling and videos.Another side yahoo messenger are best cat and cheek the mail.The yahoo and Skype are most important internet users.
Skype is the best for Calling Video calling and sharing screen. Yahoo is best for chatting and joining chat rooms
I use Skype, Gtalk and Yahoo messenger all are helpful for my business, if some clients use Skype then I chat with Skype, if some client use Gtalk, I use Gtalk.
recently , I get news from radio . that skype has been promoted important than msn, so now , having an skype ID is so important and necessary in commerce.
I think Skype is generally a nicer user experience and less spam orientated. I know when some people think of Yahoo Messenger they think of spam, bots and other nasty things. Skype generally doesn't have that conception.