MSN is a lot better than Yahoo! MSN offers far better interface, Yahoo! is way too slow at times. Lacks emoticon packages whereas MSN has tons of emoticon packages and softwares like Messenger Plus!
I am using both for last 10 years or so. Frankly I like both. I don't see much difference from usability point of view.
I personally like Yahoo mail, but I mostly use hotmail, as it offer email service for private domains too.
Well, for mailing and chatting I always loved Yahoo products only. I don't like interface of MSN much. And so using Yahoo from beginning.
I am using Yahoo mail and it is better than MSN mail. Google mail is much better than all other emails.
yahoo is the pioneer.. both yahoo and msn are too heavy to load.. gmail is the best! simple, light, and user-friendly.. just my opinion anyway.. the choice is yours..