#1. They have a more sophisticated means of looking for opponents; Besides, their 'quick-match'; Of at least, 2 different, time-controls.
{If, per chance, you don't know what exactly I mean; One can always, check it out, for themselves; On their 'quick tour,' for new players}; eg. http://www.chesscube.com
 
#2. They give both players, the pre-configured, option, of playing, the same opponent, for at least, two additional, games; Perhaps more!?
 
Unofficial #3 reason: With about, 17? times, the number of players, logged-on; Compared to this site..{how did that happen?; Considering, they've been online, less than 2 years!?}.. Mini-tourneys, for 'cubits'.. are occurring, Far more often. {for myself, that factor doesn't matter; Though for some, it does!}.
 
Unofficial #4.- Gosh, I like their standard, board & pieces, interface!; With their more exquisite, 2 different, audio-sounds; Of moving a piece, and 'capturing.'
 
Giving, credit; Where credit is due! - They Don't have, multiple, bulletin-boards..{their stupid 'chat' applets, don't count}; Unlike, this site. - 'B-R-A-V-O!!' -