If it Weren't Bryan Cranston, Who Else Could Best Pull Off the Role of Walter White?

Supposedly, Bryan Cranston wasn't even the first pick for the role of Walter White in Breaking Bad: John Cusack and Matthew Broderick (!) were the producer's first picks. By just about all accounts (mine included), Bryan nailed the role, and showed far more talent than anyone probably gave him credit for previously. It's a good thing he got the part. But what if he, too, had turned it down? Which of these alternates (and I'm including the producer's first two choices as well) do you think could best pull it off in his stead?

Basically who could be both mild-mannered, bumbling, and professorial like Walt was, and dark and badass (maybe surprisingly) like he became, and of course pull off the transition smoothly?

Discuss here