As a DM I've always found it more rewarding to make my own world. Naming and describing every spot on the map is a lot of fun for me, and I feel more of a sense of control in my own world. I don't have to memorize a lot of information about many places, I can really just make it up as I go along and write my own history and cast of characters.
It's really up to you. If you're not too into the idea of building a world from scratch, D&D and Pathfinder provide some pretty rich worlds.
Greyhawk. The first, the original, the best. LOL
Master Arminas
Ponyfinder.
With Golarion as a close second.
To me, both Paizo's Golarion and WotC's Eberron are very inspiring campaign settings.
Eberron has to be my favorite so far.
I really like Privateer Press's Iron Kingdoms. Although I'm now playing in Golarion and loving it.
from Fantasy Flight Games.
It had a pretty awful TV movie made about it a while ago (which is now on Netflix), but the setting is pure gold.
For a basic idea, imagine Middle Earth. Now imagine if Sauron had won. Now fast-forward 100 years.
It's the most grimdarkest fantasy setting I've ever seen and it's fantastically designed. I highly recommend picking up a copy (since they're out of print and cheap these days)
1. Darksun (2nd ed. not 4th)
2. Spelljammer
3. Planescape
4. Good old FR
My choice of favorite campaign setting is dependent on the setting to capture my imagination and be a medium for me to tell a story.
In no particular order, my favorites are Golarion, Forgotten Realms and Eberron. I have tried other settings but they don't fire me up like these three.
1. Homebrew - Cause I get to pick and choose from the other worlds.
2. Grayhawk
3. Ravenloft
4. Darksun
5. Golarian
I know some people knock it, but I really love the Forgotten Realms setting.
I still haven't had a chance to play in them, but I also really like the Eberron and Midnight settings.
Honestly, though, my friends and I mostly play in homebrew settings.
Homebrew.
from Fantasy Flight Games.
It had a pretty awful TV movie made about it a while ago (which is now on Netflix), but the setting is pure gold.
Hey! The Legate was quite good, so was his spy/rogue sidekick.
For a basic idea, imagine Middle Earth. Now imagine if Sauron had won. Now fast-forward 100 years.
It's the most grimdarkest fantasy setting I've ever seen and it's fantastically designed. I highly recommend picking up a copy (since they're out of print and cheap these days)
Yup, good old Midnight is fun if you want something darker and grimmer than regular D&D - no magic shops, no friendly temples, no easy healing, casting any spell is desperate move as it can attract attention of evil priests, getting food and equipment is hard. Real challenges on every step.
When it comes to things close to D&D my current picks are: Forgotten Realms first and Eberron second.