Frodo,
I'm not prepared to make an endorsement in the PA senate race. We have at least three fine candidates running for that office. I'm leaning toward
Rayburn Douglas Smith at the moment. This guy's a real Libertarian. Not that I'm a Libertarian, but I do know one when I see one.
As for the ideal Libertarian, you should probably ask a Libertarian. I liked Browne and Badnarik. I actually voted on the far left in '00 and for Bush in '04, but I will say that I respected both of the aforementioned Libertarians.
Johnson's a Republican, not a Libertarian. Ron Paul is as well. Never forget that. Not that there's anything wrong with either of them (I voted for Paul in the Iowa caucus in January 2008 and again in January 2012), but they are not Libertarians, any more than Ralph Nader is a Green Party guy. (Ralph Nader at least had the decency to make that clear when he accepted their nomination in 2000. He said he'd run under their banner, but that he would never become a member, and he wanted to make that clear to all his voters.)