My favorite old games were probably the Wizardry games. Kinda dates me a little huh. I remember having detailed maps I made, probably still do in some box. Hard to say what my favorites since then are. I enjoyed the first Star Wars and Tie fighter. I really love playing all the mech games. Of course Doom and Doom II ruled. Quake is ok, but after logging many hours on Doom II. Just wasn't all that cool. Unreal was the first "new" shooter style game. I played a few flight sims starting with one of my favorites, F-19 Stealth fighter and its sequel F117a Stealth Fighter and then F-15 and Falcon 4.0. But the game I have played the most is Need for Speed, High Stakes. Second to that was Ultima Online.
Well enough ranting.