I prefer Yahoo and Skype. But i use yahoo msgr more.But digsby is best as it supports multiple chat clients
It's a little hard to say for sure, but Skype is definitely on the rise, and it's my messenger of choice.
I personally prefer Gmail (Google Talk) and then AIM. I know everyone else uses MSN. So I just use Pidgin to talk to everyone
This is so true but at a business level, I think Skype has the number one spot, following by either MSN(Windows Live) or GTalk.
Alot of people and alot of opinions, i think the mos popular IM's are Live(aka MSN) or Yahoo Messenger. ICQ was quite popular some time ago