There's bloody billions of them in the internet, which one is number 1, in your opinion?

One of the mods that I liked best was the Aliens: Total Conversion mod.

The graphics were slightly ropey, but passable. However, the atmosphere it conveyed was definitely that of the Aliens movie.

I've played all the noteworthy ones from 1993 to July 1997 (I play them chronologically), and the best ones I've played so far are:
Hell Revealed
Momento Mori II

But lots of good WADs have been relased since 1997, and the Doom modding community is still thriving

I've just watched one of the levels in YT.
Good stuff.

Speaking of which, I just finally tried Final Doom. Those campaigns just feel so lame. I can't believe they actually dared to sell those in retail. ... Then I go and play the Brutal Doom campaign and it's like "hell, yeah!" ;) I must say they did a superb job with that one.

Are there any user-made campaigns that match BD's quality?

I'm definitely still going to try some of these older ones.

Project Brutality with the Brutal Doom starter pack wad. I like using the Ultimate Doom Visor mod, on account of the neat HUD and motion detector. ZDL is my launcher of choice for managing these things.

Not technically a wad, however the Samsara multiplayer mod is pretty good.
http://forum.zdoom.org/viewtopic.php?t=33219
It basically allows you to play any WAD using the character/weapons from Wolf3D, Heretic, Hexen, ChexQuest, Quake1 or Marathon series.

I remember making a whole bunch of multi-player deathmatch wads, unfortunately i can't find them hardly. I have maybe 1 that i know is mine and the rest don't look right, can't even be sure they were mine. Sorta sad, since i did this stuff 20+ years ago. Although i COULD make more wads again thanks to DosBox and an old Doom Map editor (which covers Doom2, Hexen, and like 1-2 other games that rely on the same engine)

Ooh, thanks for the link. Bookmarked. I know I ran across this some time ago and I forgot about it again. Oopsie!

Thanks for your link. I was get this game on scdkey last night. It is really a nice game. Some of the game playing is very exacting. I tlike it and more and more friends of my are join this game too.

Watch those corners. Watch those corners.

Yeah, Aliens TC was and still is one of the best shooter mods ever. Had a blast playing it.

Chillax for maps.
Real Guns Advanced Refined 2 and Russian Overkill for gameplay.
Also, Brutal Doom obviously.
DoomZ (older releases) for total conversion, its survival on the island with minecraft-like building.
Also, speaking of minecraft - Doomcraft.

Zandronum for engine =)

My number one are two*: Chillax+RGA2 and DoomZ.
*"I want a two number ones, number five with extra cheese, double number 6" just like Big Smoke xD

Number one? Impossible to say. There are soo many good ones. At the same time, they're so different, I can't compare apples to bananoranges.

In no specific order, some of the best / my favorite (some quite recent) wads:

Ancient Aliens (Boom compatible)
https://www.doomworld.com/vb/wads-mods/87784-ancient-aliens-rc2-available/1/

Valiant (compatible with at least PrBoom+ and ZDoom)
https://www.doomworld.com/vb/wads-mods/71704-valiant-wad-now-on-idgames/1/

Back to Saturn X Episode 1 (Vanilla compatible)
https://www.doomworld.com/vb/wads-mods/62529-back-to-saturn-x-e1-99i9-plus-new-unheard-midis-on-page-13/1/

Back to Saturn X Episode 2 (Vanilla compatible)
https://www.doomworld.com/vb/wads-mods/69960-back-to-saturn-x-episode-2-public-beta-2-critical-map15-fixes-included/1/

Doom the Way Id Did (Vanilla compatible)
https://www.doomworld.com/vb/wads-mods/58100-doom-the-way-id-did-v1-1-released/1/

Doom 2 the Way Id Did (Vanilla compatible)
https://www.doomworld.com/vb/wads-mods/66113-doom-2-the-way-id-did-released-bugfix-update-nov-16/1/

Sacrament (plays great in PrBoom+)
https://www.doomworld.com/vb/wads-mods/55347-b0s-presents-sacrament/

Sunlust (Boom)
https://www.doomworld.com/vb/wads-mods/68089-sunlust-on-idgames/1/

Deus Vult (Limit removing? Runs great in PrBoom+)
https://www.doomworld.com/idgames/levels/doom2/Ports/d-f/dv

Deus Vult 2 (PrBoom+, (G)ZDoom)
https://www.doomworld.com/idgames/levels/doom2/Ports/d-f/dvii-1i

I'd also take a look at Plutonia 2, A.L.T. (for weird russian stuff -- see also Sacrament), Alien Vendetta, and many others... if you love big detailed open cityscapes, check out Lainos' maps.

If you liked Valiant or Ancient Aliens, check out Vanguard and Lunatic.

Oh, Doom 2 in Name Only: https://www.doomworld.com/vb/wads-mods/62339-doom-2-in-name-only-now-supsiciously-on-a-load-of-gaming-articles/1/