My vote goes to Picard. It's not easy to choose because, except for Archer, who seems a little too naive most of the time, all the other captains each have a set of qualities that make them remarkable. I see them as alternative answers to the question "What makes a good captain?". One is not necessarily better or worse than the other.
But, if I had to trust any of them with my life and if I had a choice it would be Picard.
I also love the idea of Captain Spock, though. The moment I saw Spock in the captain's chair on the Enterprise bridge (in "Wrath of Kahn" if I'm not mistaken) was extremely rewarding. I think Spock is the real captain of the original Enterprise anyway, so he fully deserved to sit in that chair.