I can't remember when I first actually played Doom, but it had to be after 1998 when my family bought our first Compaq PC. Some shareware disk with Doom 95 on it probably.
However I never really played the game until the last couple of years with ZDoom. I've only ever completely finished the first episode to be honest, because I find the level design to be pretty uninteresting and flawed by today's standards. But nonetheless, I'm hooked on the simplicity of the gameplay and looked around for some interesting WADs of maps or total conversions.
This page has some of the all time greatest WADs supposedly. I'm still going through the list looking for something fun to play.
Any Doom fans out there with suggestions?

Ah, Doom. One of the finest FPSes. Your post made me want to go back to Doom again!

Well you could get the Doom64 TC that adds a new flavor to Doom 2 entirely. I am not sure if that would be your thing but it is free and nearly painless to install. The name of the TC is Doom64: The Absolution or just Doom:The Absolution. http://www.doomwadstation.com/doom64/index.html. Try this one. It should have the main WADs for Doom 64. Take note that you still need a Doom 2 WAD to play this.
Also, ever tried hacking those old WADs just for kicks and grins? I used to hack mine to make a chaingun shoot shotgun bullets. Cyberdemons died quickly...it was a better weapon than the BFG.

I got Doom and Doom 2 again from Steam for only $2 on Christmas sale. It was great!

My first shooter was Wolfenstein, though I enjoyed Doom much more... until Duke Nukem arrived. Then, HE was the king. I still have the 500 levels expansion for Duke Nukem.

"It's time to kick ass and chew bubble gum... and I'm all out of gum."

Aliens TC rocked. It probably sucks now, but back when i played it, I followed the instructions in the readme to the letter. Set the sound so i could just barely hear the music, turned off the lights, scared the crap out of myself.

Me and a mate actually made a doom WAD, as a homage to Kingdom of loathing (a crazy browser based pencil drawn game) that was pretty cool,
we had a midi of children of bodom: bed razors playing in the the first level :D fitted really well!

With the complexity in first person shooters ever increasing and more focus on competitive multiplayer, a lot of the essence of pacing and rhythm has been lost from singleplayer maps. I see a good oldschool map such as in Doom to be like a song and less of just a pure test of your skills. Like a song, when all the aesthetics, architecture, ambient sounds, and pacing fits together just so perfectly, you can play it over and over and still come back to it.
Granted, I find many of the maps in Doom to be less than playable, but most of the Episode 1 are pretty unforgettable.

Alien Vendetta \o/ Awesome wad, along with Hell Revealed 1 & 2. I'm too lazy to find links though...
Also, try AEoD.

Just a short list of the ones I can remember playing that were kind of fun.
Fistful of Dollars
[url=]http://www.doomwadstation.com/main/fistful.html[/url]
Its very short but well done. I think it was 1-2 proper western levels and then a less realistic boss level. Worth playing at least once.
Aliens TC
http://www.doomwadstation.com/main/aliens.html
Someone mentioned it earlier and it is still fun to play. Check those corners!
James Bond
http://www.doomwadstation.com/main/ge.html
I remember this being done fairly well and was good fun.
Starwars
http://www.doomwadstation.com/main/starwars.html
Starwars TC is very well done for a doom tc but its hard as hell. I think it took me a couple trys to complete the first mission on this one, you have to be very careful.