Of all the possible 2016 Republican nominees yet considered, Ryan probably has the strongest governing credentials, namely real experience in an important legislative body. In comparison to other Congressmen like the himbo Rubio, he doesn't really have any competition on the experience front.
He's also an ideologue. Until today, I'd have said he was the most by-the-book conservative the Republicans could nominate four years from now. However, with his recent minority vote for the fiscal cliff plan, I may have to revise my consideration of the man.