My primary game system is 5e D&D, though I'm open to attempting almost any system.
I enjoy horror, dark fantasy, and urban fantasy games with a heavy roleplaying element. I'm particularly partial to investigative roleplay, strategy, and resource management. I love a DM who holds the players accountable for the choices they make prior to entering the action, and who appreciates out of the box thinking on the part of their players.
I like settings with few bells and whistles. The setting shouldn't be more complicated than the characters or the plot (at least not on the surface). If given the choice, I'll take a simple homebrew over most of the published D&D settings. The exception is Ravenloft, of which I am particularly fond.