Honestly, it depends on the situation. There are plenty of situations where I'd pick Kirk to lead in a heartbeat. There are just as many where I'd pick Picard or Sisko in a heartbeat. If you put a gun to my head and told me to pick one, I'd probably go with Sisko. The dude had his wife killed by the Borg, and his son nearly killed, and then went and built a ship whose entire purpose is to kick the Borg's butts. He ended the Dominion, became a god, and is just an all-around badass.