I’m not a fan of his father (to put it kindly) but I hope Rand Paul wins. He might be more libertarian on foreign policy issues than I’d like, but his limited government stance far outstrips that.
On some foreign policy issues he is a little more hawkish than his dad. So, for me -- it's sorta like you get Ron Paul's free-market, federalist domestic ideals, but with a little more realistic pragmatism and willingness to work with the team... and with somewhat more willingness to "shoot back" in foreign affairs. (Somewhat).
That's my general impression, anyway.