The glib answer would be the fans. I think Baer, while no fancy dan, is still the better boxer and I think he has the better chin and probably more stamina. I like him to outlast the Bull in a slugfest.
As sloppy as he may have looked in there, Baer still wasn't as crude as Firpo, and I think he had the sturdier set of whiskers. Baer by KO in a sloppy, up-and-down showing.
In my opinion Baer would be the favourite, too. But he should be serious and train hard! Firpo had knock-out power.
Baer is a total class above Firpo, who was mostly hype, to make Dempsey reign look half-decent. Max Tko 6.
Baer would destroy Firpo, and early. Not that Firpo is as useless as some like to make out (or as good for that matter, how did he become such a contreversial figure?) but think of it this way; Firpo is easyish to hit. Dempsey is a better composite puncher than Baer, but Bear hits harder overall. Baer also has a better chin. Baer KO 1 or 2. Of course that's under perfect conditions etc. The fact is that Baer could be pretty sloppy and sometimes lacked focus. Here, Firpo has a punchers chance, so gambling on this one, whilst a good bet would be heart in the mouth stuff when the bell rang.