can't say I actually watched but I would've if had been on, but Mariota was excellent while Winston was about what I would've guessed, multiple INTs. I think that will be the story of his career.
RGIII is. I would not go so far as to say Winston is, just yet. He has time to learn. Mariota is no guarantee either, although I do like him better then Winston or RGIII.
One good game does not make a career. RGIII was a sure thing after his first season. Now he's struggling to just stay with the Skinz. You never know.