which chat tool do you think is the best one?

Nowadays, a variety of chat scripts have appeared. Some are free, others need fee. And, some are fit for personal use, others are satisfied with the businessmen. In the following chat scripts, which one do you like best? Tell some reasons in detail.
1.123flashchat
2.tufat
3.E-meeting
4.bold chat
5.userplane
7.msn
8.skype
9.others