Right now, Marvel Earth is lots less powerful than usual. Lots less mutants, no Jean, Xavier, Magneto, etc. The only top-tier guys that could hang with any of these 3 are Sentry and Doc Strange. Maybe Black Bolt or Hercules because he has some familiarity with them.
Still, 3 vs. a lot of heroes would be tough. So Earth takes it the majority, but finding an answer for Odin would be tough as hell.
I think Odin, Thor and Loki can take them. As Digi was saying, I really don't see anyone but Strange Sentry, and maybe Herc putting up a real fight, and with Prep, they would figure out a way to neutralize each of those targets first. With Doc and the rest of them out of the picture I don't know who is left to take them on. Odin is just too strong and smart. Also Loki could devise some great plans I think with some prep and Odin/Thor's help. don't count him out.
Sentry goes toe to toe with Thor
Dr. Strange holds back Odin if he's given prep (as he did against the power of the IG wielded by Adam Strange)
As for Loki... Doom... :P assuming Dr. Doom is willing to help the heros.... he is called the second most powerful sorceror after strange after all....
also even Mr. Fantastic cloned Thor... and the Cloned Thor was about to do massive damage... it might be able to do damage against the 3 gods...
i'd say as long as strange comes back from the artic (which is where he apparently is during the whole civil war) then earth wins 7/10... but without dr. strange... we all die.
__________________ Quotes from Hia8:
"I claimed that the science is sometimes faulty."
"You don't understand. This is fiction. That means none of this stuff really happened."
"There is no writer to purposely ignore a character's natural ability just because it suits the story."
"in some cases because the writer knows that Character A will dominate Character B easily and refuses to allow this to happen for the sake of the story."
At first, I thought the Asgardians would take this at least 8/10, but thinking about it, while the other heroes are fighting the gods, it would be giving people like Reed and the FF prep time to counter the threat. People like Forge and Doom getting resources and wierd tech, I think Earth can pull at 6/10 without Strange.