I nominate Picard: 10 deaths.

• "Lonely Among Us": Picard exists for a period of time only as some sort of energy field out in space. He eventually gets saved by the power of terrible sci-fi. I file this under "temporary death", even though his consciousness still seemed to exist...somewhere out there.

• "Time Squared": Picard kills another Picard.

• "Cause and Effect": OP has already mentioned this one, and so no need to explain.

• "The Inner Light": Picard dies of old age in the alternate life that the probe gives him. When he dies, he wakes up on the bridge of the Enterprise.

• "Tapesty": OP already mentioned.

• "Chain of Command": Presumed dead after being captured by Cardassia.

• "Parallels": Picard is dead in various alternate timelines. The deaths are not shown on-screen, but that seems to be okay by the guidelines of the question. Also by the guidelines, this gets counted as one death (no matter how many timelines he dies in).

• "Gambit": Picard is declared dead after he is "killed" by a transporter weapon.

• "All Good Things": Two Enterprises blow up (presumably ending two Picards). Will count as one death.

• "Generations": Picard looks to have died on Veridian III (due to explosion of the Veridian star) just as Kirk seemed to have died aboard the Enterprise-B. In actuality, Picard was saved by the Nexus (just as Kirk was), and we find this out a few moments later.

Even if we discount "Lonely Among Us" and "The Inner Light" as fringe cases, that's still a whopping 8 deaths. Accordingly, I claim that Picard has died the most.