mine is Greyhawk.it's a simple and fun setting and it was my first as a player and as a DM,even though Wizards have discontinued it.but I love Greyhawk and it's my all time favorite.

Dark Sun and Planescape.

But for PC games I guess Forgotten Realms is very good too.

Greyhawk - I only played Temple of Elemental Evil (PC), and it's as good as FR.

Goldbox FTW!

Mine is Eberron. I didn't start playing D&D until five years ago (and I've been playing the same campaign since), so I never really got into AD&D or 2E and therefore didn't get to play any older settings.

But I love steampunk, I love noir, I love Raiders of the Lost Ark, I love dinosaurs and I love pulp fiction, so Eberron is a perfect fit. It's like someone added everything I like into a setting.

I like Forgotten Realms just b/c there's so much source information. It feels very lived in.

I'm less fond of v4.0's reboot of it due to the cataclysm changing everything, but it's still okay.

Planescape. It's just so unique and interesting.

Planescape, because not only do I love the look and style of it, but I can also use most of the other campaign settings too. I feel like dropping you into Aebrynis, or Athas, or how about motherfucking Ghostwalk? Portals.

I'm also a Ravenloft fan.

Shadowrun is my favorite DnD setting.

;)

Ravenloft is my favourite

Planescape. Because it's unique, dark, a little more mature and grey-scaled (despite its emphasis on alignments), pseudo-philosophical, with lots of intrigue, a bit steampunk-y and it offers lots of different possibilities without feeling as cobbled together as the Forgotten Realms ("This morning I fell into the latrine pit and guess what, I discovered the ruins of an ancient kingdom beneath it, swarming with monstrous armies and supervillains that plot to take over the world and/or destroy the universe!" - "Oh yeah? I had the very same problem only two weeks ago. Nasty buggers." - Not that this couldn't happen in Planescape, but at least dimensional travelling would be involved. ;) ) Oh, and artwork by Tony DiTerlizzi. :)

My second favorite setting is Ravenloft, and Dark Sun seems interesting too, but I've never really been into it.

i guess i'm going to be the odd duck here and say the Dragonlance world. First of all I grew up on the Heroes of the Lance books and was totally immersed with the characters of that world. All the novels were really great. Planescape, Ravenloft and all the Forgotten Realms were great but to me, Dragonlance embodies what "classic" D&D was all about.

Plus they had the Draconians :)

Strictly based on DnD videogames I have played: Dark Sun and Ravenloft.

There was a Dark Sun game? And a Ravenloft game? I've never heard of these before. That's awesome.

I always had a soft spot for Hollow world.

It was the first really unique game world I found.....