I play all the modes, though rarely go into a Capture the Flag anymore.
I have been enjoying the 2v2 mode most lately but also 4-player Match of Champions is a blast too.
Thread title says what I play MOST, so that answer is Team Favor of the Gods.
Favor of the gods 4v4, I don't play much match of champions because there is always someone to wait until everybody is weak and come with a huge area attack.
I enjoy playing capture the flag when both teams have 4 players (there is always 1 missing) and really play as a team. I started playing it to get manticores armor and got the highest amount of kill I've ever seen: 17 kills and 3 deaths (1 suicide) and still captured the flag during sudden death