RTS games are the best for competition.

RPG is the best for feels and consuming large amounts of hours at at a time.

Adventure is pretty cool, to be honest the most memorable adventure game is
Star Fox Adventures, it was pretty neat when I was a little kid and my sister did all the playing.

Overall, I would rather playing, while alone, a RPG like chrono cross just because it feels so in-depth and deep.

But for my current all time favorite, since online games are what is my favorite these days, I like Graal for community and I like BF4 for casual play. (I am actually really good at shooters for some reason, when I am actually trying)