McCain, hands down.
McCain may be a "maverick" but he is a pretty solid conservative in my book.
McCain: On the IssuesPro-death penalty.
Anti-abortion on demand.
Anti-drugs.
Pro school choice.
Anti-Kyoto.
Pro-free trade.
His one strike in my book is campaign finance reform, which was simply handling wrong. It was probably a good idea, but the result was simply worse than the problem it was trying to fix.
All in all, McCain is a mainstream conservative. He is more conservative than President Bush in my opinion.
I would vote for him without hesitation.