I have yet to complete Doom 64 (working on it) so it's not on this list.
Doom 2 - This is what my dad had so this is what I played the most growing up. (I'm 28 now) Beating it for the first time on my own was immensely satisfying.
Doom - Only had Knee Deep to play for years until I eventually picked up Ultimate Doom. I very much enjoyed it but since I spent most of my time with Doom 2 before hand I really missed the newer demons while playing.
Doom 3 / Doom 16 - I love them for very different reasons. The atmosphere of Doom 3 is fantastic and I usually eat that shit up in video games. Doom 16 isn't a slacker on atmosphere either but the gameplay is fuckin' addicting in a way Doom 3 isn't.
TNT - In my brain this was always the 'conclusion' for the original Doom games story wise. Not quite as fun but the music and vibe of the game always really clicked with me.
ROE - I liked it, but I didn't love it.
Have yet to complete: Plutonia because I'm lame. Doom 64 because I never had an N64 but I got it on my PC now and i was working through it until the new game came out.