I think Mcallister was the best choice for Red John.

This is not an opinion on how episode 8 was executed - I agree it could have been better and some important things should have been answered in more detail. Maybe the final version will have more explanation. But reality is that on Sunday I think we will see pretty much what was in the leak. Some specific clues were not answered but in general the sheriff fits the clues as Red John.

Here is my reasoning:

Red John is a showman. A showman is an act and Red John would ultimately have to be an ordinary man. Therefore, the season 3 finale for me would not be a fitting end to Red John since it was too much 'show' and not real. Also RJ dressed as a dumb sheriff would be an great act. I liked the fact that Red John was an ordinary man, not some God compared to Jane. I liked that in the end he was vulnerable and flawed, just like Jane. I think the writer's point is to build up Red John as some powerful God, but then show in the end he has to be an ordinary man - he can be shot, tricked, fearful. The fact that he is on the list and revealed to be the ordinary sheriff is totally in line with this.

Occam's Razor - simplest solution is usually the right solution - the physical description pretty much matches and is explainable (loss of hair). Red John would want to be low key and out of the public eye (this was stated many times by Partridge - Red John has been laying low) - a power behind the throne - so the small time sheriff in Napa seems a good way to go. He was the only person gaming Jane and wanting to be his friend or follower in season 6. He is a hunter and likes killing and can be invisible (as shown in s01e02 and s06e03). He is self-possessed and calm.

Bertram is out - too high profile, too tall and big.
Partridge is out - dead - Cho himself checked the body and to think one of the core team would not notice/suspect a fake body is disrespectful. Plus if body was fake, RJ would have had it destroyed before Cho got to it. 
Kirkland - dead. Any twin theory is too much of a complication so far into the end.
Smith - physically unsuitable, too much of a hot head.
Haffner - the only other possible/believable option - but came in late, was humiliated out of CBI by Jane, too outwardly emotional, publicly doesn't like Jane.
Styles - not an ordinary man, too public, too old

Also Heller said there would be no tricks, and I kind of agree - in the real world he has to end the story line so some long running big twist throughout season 5/6 and revealed in ep. 8 is really unlikely. It has to be someone from the list, someone we have seen from the beginning (s1 or s2) but know the least about. It just makes filling the clues easier as a writer.

Red John has been described as sadistic, lonely, tormented, arrogant. To have that proven right through an ordinary man Mcallister, this is a winning end for Jane.  And this is what it's about - not Red John being some mighty God who has in the end bested Jane. But Jane proving Red John can slip, can be tricked/beaten and Jane to exact his revenge on a broken arrogant man.

I just wish there is more of a backstory to Red John instead of pointless noise about Bertram, the FBI etc.