There are a few US/canuck actors who appear able to drift from wooden to awesome, and it's often hard to pin it down to directors, script, production or editing.
Mel Gibson springs to mind, along with Donald Sutherland, Alan Alda, Brad Pitt and Barack Obama.
As for consistent ones, I would include Smash's list, and add Danny DeVito (laugh all you want), Morgan Freeman, and even Matt Damon. Even in movies that aren't my cup of tea, they appear to give performances that do exactly what's asked for.
My No 1 over-rated actor?
Jeff Gold(tortuous pause. . . . . . . . . . . .)blum
____________________________
"I started out with nothin' and I still got most of it left" - Seasick Steve