Hands down it was Ronald Reagan. The country was in an incurable funk and his administration cured it.
But ya know, things were pretty good under Clinton too. But that's cuz after his failed attempt at health care reform, he behaved like a moderate Republican (i.e. fiscally responsible and not afraid to invade other countries) and things were good.
Bush was BY FAR the worst, with Carter being second worst. Carter was a good smart person, but his administration was totally ineffective.
Obama has a good team, but he's far and away the most unqualified person to hold the office since .... since .... since the 19th century. And you can tell he's in over his head.
So there's no real formula, so much depends on the attitudes of the party in the white house and the parties controlling the house and senate.
Chris