For me, I'd have to say Old School X-COM (UFO Defense, TFTD, X-COM Apocalypse to an extent). I love them in a way that I just do not enjoy NewCOM, but the interface was quite possibly based on the recovered works of a 13th century scribe, and is very difficult to get used to for an unfamiliar player.
Doom is so fucking good! I find that I really prefer modern controls. Even clunky ass Wolfenstein slaps with fully modern controls. A lot easier though lmao