Clark Kent/Superman: Christopher Reeve
Lois Lane: Terri Hatcher
Lex Luthor: John Shea (this is a hard one; before watching L&C I would have easily said Michael Rosenbaum)
Jonathan Kent: John Schneider
Martha Kent: Anette O'Toole
Perry White: Lane Smith
Jimmy Olsen: Michael Landes
Jor-El: Marlon Brando
This is an interesting list because, for me anyway, it shows what versions handled what aspects of Superman the best. The movies excelled in the larger-than-life superhero aspect, messiah parallels, and the history of Krypton. Lois & Clark best showed life in Clark's everyday life as a mild mannered reporter in Metropolis and his supporting cast at the Daily Planet. Smallville is great at showing the influence and importance of his adoptive parents, and brings out Clark's struggles of using his powers for good, but also his wish at times to be normal.