To me there are two distinct "Breeds" of Dungeon Master - "Pimps" and "Whores".
There are "Types" of DM too - whether they be active, passive, reactive, cinematic, or dramatic - they are always either Pimps or Whores.
The "Pimp" will only ever run Games that HE likes and is passionate about, whether they be older editions of a specific system or retro-clones of that system - and he talks up his fave to the Nth degree - getting players to join his games, his players ALWAYS get into it because he is so passionate about what he's doing!
The "Whore" sells out, runs whatever is new and shiney - whether its for selfish reasons (he really REALLY likes the system, there can be some crossover into "Pimpdom" here), "because its new and shiney" (the true Whore), because "thats what everone else is running/playing" (the "Keep up with the Neighbours" Whore), because its a new edition (the "want to be part of something bigger" Whore).
Are Pimps superior DM's to Whores - not always, its not about that. Its about "pushing" an inferior gaming experience.
Thats not to say Whores can't run AMAZING Games, but True Whores RARELY run home-grown Scenarios. They are always "up to date" with the new scenarios and campaign supplements.
See, when I started there wasn't that much in the way of Campaign Worlds - so I could quite literally move between groups and never have the same gaming experience - it was wonderful seeing all that creativity and passion.
I've joined in with a few 4e Games, and - to be perfectly frank - they are pretty much clones of each other. Dissapointing really.
Whether you are a Pimp or a Whore, you should always do your best when running games - its important, and pretty much your biggest task as a DM. Because if you don't care, how can you expect your players too!