I'm completely torn on this one. On one side, there is HBK, one of the best ever. On the other, The Rock, one of the best ever. Thus, I'm torn.
Athletically, The Rock is really well conditioned. Michaels really can go, but has had injuries, where the Rock really has kept a near perfect track record throughout his career. I'd give the slight edge to The Rock here, but that doesn't mean too much. After all, this is a timed match, and this could give the advantage to the smarter wrestler, not just the one in better shape.
Another way I like to look at this is that both men are chronic losers. Both have pushed through feud after feud and been the overwhelming favorite, however, they would come up short (via screwjob, interference, etc.). Sure, both have enjoyed a great amount of success as World Champion, Intercontinental Champion, etc., but both CAN come up short when all the chips are in play. This is what makes the match so hard to decide for me, as neither man plays the "Superman" character that cannot lose.
So, in my best opinion, this is how I'd think it to play out:
The Rock would come out like a beast. He would definitely match Michaels move for move and possibly even outmaneuver him in the early going. I doubt however that this would lead to any quick falls, as both men have been known to kick out of almost anything. Through the mid-portion of the match, Michaels would get his second wind, while The Rock would start to slow. Again, I can see the typical HBK setup, all the way up to tuning up the band, but Rocky would likely just counter into a DDT or something.
Still, to the end, I can't see either guy really beating the other. To argue the contrary, IF one guy were to beat the other early, I could easily see the other guy tying it up in the midsection of the match. Either way, score or no score, I think this one comes down to the wire, possibly even to OT. Here, I think I'd give the edge to HBK, and it is really difficult to say why. I think it may be my memory playing tricks on me; making me think that The Rock lost in this scenario more often than not. However, HBK has his share of losses in the bottom of the ninth as well.
Perhaps I keep thinking back to the Ironman match of Michaels VS Hart, and Michaels' so-called "Nineteenth wind." Perhaps I keep thinking of the matches that The Rock lost, to the likes of Austin and Triple H. I think it is a bit unfair to compare Ironman match experience, as The Rock's was so littered with outside interference that I can't really say the result was fair. Either way, I think I'm going to hold my vote for now, and read into what others say. Perhaps I'll be swayed. Perhaps I won't vote on this one. Maybe I'll flip a coin, as I doubt either will run away with this one.