Picard. He's in far more control of his crew, in my view. Mind you, I've only seen both Kirks and Picard in action, so it might change when I get around to the rest. I also prefer Picard's crew.
Plus, I can't figure out who would play an adaptation of Picard to replace Patrick's quite frankly awesome performance. Kirk is slightly easier to have someone recast (not that they ever should, or should have!)