Hello! Just a fellow Lego enthusiast here. I'm a big fan of the Adventurers, Arctic, and Ninja themes.

I also really enjoy the evergreen themes (castle, town, space), mostly from the late 80's and the 90's.

Castle: Lion Knights, Royal Knights, Black Knights, Dragon Knights, etc...

Town: Leisure, Coast Guard/Boats, Police, RES-Q

Space: Blacktron I, Unitron, Exploriens, Ice Planet 2002, UFO/Insectoids

I love unusual/rare/prototype pieces as well, especially when they can be used with my favorite themes :)