Kirk by himself isn't that great of a Captain, it's only as part of the Holy Triumvirate of Kirk, Spock, and Bones that he's the best Captain. Picard is only an OK Captain, he's too much of a European Captain, the best Captains are cowboy Kirk and The Sisko; if Janeway's megalomaniacal plans of galactic domination had ever played out, then I guess she'd be the best Captain by default, so it's a good thing Harry Kim was there to sabotage her. Archer, we don't talk about Archer... I think Porthos would've been a better Captain.
Picard seemed to embody more European socio-cultural values, he seemed very much in the mold of a European diplomat/statesman with a somewhat aristocratic bent, a strict adherence to protocol and rules, and an emotional detachment from his crew, and had a very "above the fray" sort of attitude. Whereas Kirk was very much the cowboy diplomat/leader type, a John F. Kennedy in space, not afraid to use his fists or a karate chop to solve a problem if need be, he gets in there and gets his hands dirty, he's down in the trenches with his crew, and will throw out rules and regulations if they get in the way of doing what's right or necessary; that's very American.