I'm gonna have to go with MSN. I think ICQ has been on it's way out. I did not like the idea you could never pick your own number. I mean it's all fine and dandy when you add friends you can assign a nickname, but come on it's too much bull to deal with. MSN is user friendly, simple, and streamline/
I prefer MSN. I find ICQ pretty much for the "older" generation. No offense >.< Also, ICQ uses numbers right? MSN is much more convenient in terms of user ID.