Live chat plugin

Hi all,

I’m prepared adding Live Chat to my website allowing registered users talking amongst them. On searching plugin I found;

FlexTalk – Live Chat
http://wordpress.org/plugins/flexytalk-widget/

15 Free WordPress Live Chat Plugins – Free download
http://phuocub.com/2013/11/free-wordpress-live-chat-plugins-free-download/

Kindly advise which of them shall I install? Thanks

satimis