A lot of people, myself included, cringe at the use of the word "evil" in these situations. It's important in factions like that to never lay on the "evil" thing too heavy or to have the game itself imply that anything like that is "evil." It's okay if the player thinks the Dark Brotherhood is evil, it's okay if the in-game NPCs call the Dark Brotherhood evil, but the game should make no assumptions.
I think that's what you meant though, so yeah, I'd like to see a guild whose actions are not generally accepted under most people's morality, but not an "evil" guild.
Exactly. But the Dark Brotherhood did kinda of seem evil(they enjoy the suffering of others, innocent or otherwise). I guess it was their portrayal though.
I have to disagree with the OP in that the DB questline was "well written". It was full of holes main thing dialog for one. The slaughtering of the other guild members totally brought me out of the story, Why would my character do that? Sure they didn't care much for the other members, but my character killed for money not for the pleasure of killing.
In that affect I never finished it, but I played through enough to say I didn't like it.
Another thing, in both Oblivion and Fallout 3 the "evil" groups were like Nazis. Especially the enclave. And no "evil" character would poison the water when they knew it would poison them.
Sorry. I've been wanting to say this for a while.