I'd be amazed if there aren't "everyone dies, Reapers win" and "everyone dies, but Reapers are still defeated" endings. Still, if I had to guess the "best" ending (turns forum flaming deflectors to maximum), at least how I've played (maximum paragon), I think it would go thus:
Krogan form shock troopers against indoctrinated slaves.
Shepard convinces the Geth and Quarians to sign a truce and form a giant space armada of badassness along with the Alliance forces to fight the Reapers in space.
The Council will whine and cry and beg Shepard to save them. Again.
Cerberus will try to screw you over at some point. Again.
In the end, good guys win (though probably with some sacrifices, unless you're just THAT badass), Shepard will give the Council the finger and tell them, "You should have listened to me asshats," then go on a yearlong pleasure cruise in the Normandy with his/her significant other of choice.
After installing a hot tub in the captain's stateroom.
Because that's totally what I'd do