What’s Your Favorite Genre of MMO?

Long ago, the term MMO had a strict meaning of RPG gameplay.  When you look around today, you see MMORPGs are still going strong, but there’s MMORTS games and their MOBA descendants, MMOFPS games, and other derivatives.  This is largely the result of the ubiquity of the Internet as a unnecessary part of our daily life, but which one is your favorite?  Of all the online game genres, which is the one that you love most?  Which did you play first?  Which one do you not like as much?  Let’s start a conversation about what games and genres are the ones we love most.