Oh man I missed the Doom vs RE debate. Oh well I'll still put in my two cents.
You guys are arguing over the wrong things. "Too gory?" "Too violent?" isn't the question to be asking. You need to ask "What can this character do that would be unique and interesting?" While I'm in the camp that Sakurai can turn litterally any character into a unique fighter, there are some characters that are inherently packed with more potential.
So I have to admit, as much as I love Resident Evil, the people you play as don't have any unique powers or weapons. And why would they? The appeal of a survival horror is that you are a mortal human trying to survive with what you got. If you had amazing weapons, armor, magic, or whatever it would ruin that aspect of the game.
Doom, on the otherhand, is the exact opposite. Doomguy has all sorts of cool weapons that are distictly Doom. He's fast, strong, and brutal.
Now which characters have the potential to be a more fun and unique fighter? Jill/Leon? Or Doom Slayer? I'm going to have to go with the Doom Slayer. I'm not saying Jill/Leon couldn't be incredibly unique and fun. Ofcourse they can! But who seems more obvious right off the bat as someone bursting with fighter potential? Doomguy can do anything Jill/Leon can and much much more. And yes, they could make them focus on survival aspects of the series, and have Jill\Leon conserve ammo or hold on to Herbs and stuff. But c'mon... I'd much rather play as the guy who can pull a bajillion different weapons out of nowhere and rampage through the stage. But that's just my opinion.