If not for that goddamned peanut farm, I think Carter would've been one of the best Presidents we could have asked for. He was always an honest man (even to a fault, ie the Playboy interview...) and would've done a lot to help the nation heal after Watergate.
OOC: Are we assuming that Carter makes it to the nomination, and then loses the general election? Or does the peanut farm stick as an issue that prevents him from becoming the nominee? I have an idea I'd like to throw out there but not if it deviates too much from the OP's intent.
Edit following OP clarification: If we'd had Carter in 76, I'm damn near certain we could've avoided the Reagan years. When the primary ended withou a clear winner, and ol' Teddy Kennedy was chosen as a compromise candidate, he only defeated Ford by a hair thanks to the whole Chippaquiddick scandal. And come 1980, he got curb stomped by Ronnie Reagan in a way that the more conservative Carter definitely wouldn't have. I mean, the good Reverend might have "committed adultery in his heart", but at least he didn't actually kill a person in real life...