Of all three choices, Stelmach seems the best fit for Premier. I make this distinction based on their "presence" and image in the media and from radio and TV interviews I've seen.
Dinning bugs me as a person. He's too smooth, too much of a politician for me. Just me, but I don't like overly "smooth" people

. I figure Dinning will spend more time worrying about satisfying his political base rather then focusing on the problems facing Alberta. He will not take a hard line on anything, but will try to satisfy everyone at once.
Morton will be a pointless leader. He is the crazy right-winger that everyone is scared of and would just cause the rift in Canada to get even larger. If he wins, the PC's will split and all the Dinning/Stelmach/Oberg types will form a new party and within a year we will be voting the new party in and Morton out. Nothing will get done at all due to the split and the rest of Canada will continue look at Alberta like we are a bunch of half crazed prarie seperatists. The majority of us are not this.
Stelmach comes across the best to me. He's sensible, logical and seems sincere. He's got Dinning's ideas, without the "politicalness". To me, this is the guy that I want to represent Alberta at a Provincial level. He appeals to everyone, but doesn't specifically represent one segment.
Keep in mind I say all this not based on their ideas, but on how I percieve them. So, feel free to rip me apart