If all the superheroes started fighting each other–no teamups, no alliances, every man (or woman, or alien, or swamp thing) for themselves–who’d win?
Anybody from DC or Marvel (and their offshoots, like Vertigo, Elseworlds, All Star, Ultimates, Marvel Knights, etc.) is fair game, and all history up to the present in is play–for instance, the events so far of Infinite Crisis are applicable. You can bring in multiple versions of the same character if you want.
Batman. If… he’s prepared.
Thank you, Askia.
Serious replies, anyone? 
Nabu-powered Dr Fate.
He defeated the very embodiment of the Wrath of God.
It’s really hard to top that.
Is the Spectre still the personification of The Wrath of God? Whichever version of the Spectre was The Wrath of God, he’s my pick.
Curse you, Tengu!
muttleylaughs
Spectre was my first choice, actually, but then I remembered Fate managed to bring him low (albiet at the cost of his own life) in the DoV special, so I had to change my vote.
Would any of the Superman analogues (Miracleman, Supreme, Sentry, etc.) have a chance against Dr. Fate or the Spectre?
In a more street-level fight, I think it would be hard for anyone, even Batman, to beat the Midnighter on a good day. Deathstroke would certainly hold his own in a fight like that too – those three in a brawl would be great, especially if sneaking and strategy could be involved.
I’m voting for Dr. Manhattan. Seriously, the guy can do whatever he wants.
What? I was serious… 
Another vote for Dr Manhattan. His precognition would give him the edge over the other hyperpowers.
Unless someone manages to deploy tachyon generators again. That seems to fuzz him up.
Course, he’s still basically impossible to kill.
Jesse Custer?
Granted, normal firearms can take him out, but he could kill Dr. Manhattan (and probably God himself) just by telling him to die. On the other hand, he pretty much loses automatically versus any superhero who can`t speak English. But how many of those are there?
Batman still beats Jesse Custer, if he`s prepared. A pair of earplugs would do it, although Custer could at least hold his own in the ensuing fist fight, IMHO. So I dunno.
Another thought…do the Endless from Neil Gaiman`s Sandman count?
That’s what I’m thinking. It’s already been decided. Death turns out the lights and closes the door when the last line has been written into the Book of Destiny. Right?
Blue Beetle. He hides in the pile of corpses until there’s only one other hero still left alive, but utterly exhausted from the battle, and cracks him or her in the back of the skull with one of Wolverine’s severed legs.
The Saint of Killers from Preacher.
He shot God dead.
Slapstick. He’s a friggin’ cartoon character fer chrissakes. Completely indestructable.
Mr. Rodgers in a blood-stained sweater.
my first impulse is always Ambush Bug.
But honestly I’ve got to go with Doctor Manhattan. He literally has the power to rewrite anything he wants AND he knows everything that’s going to happen to the universe ever. It’s a winning combination.