A quick sum up of some important Loghain facts
-Very traumatic childhood. Joins Maric/Rowan, fights off the rebels, sacrifices his own happiness to get the Orlesians out of Ferelden.
-Distrusts the Wardens, especially after the events of The Calling. Understandable.
-Hates Orlais, and with good reason, I might add.
-Wants to keep his daughter on the throne.
-Practical. Logical. Almost masochistic in his sense of honor and duty. Not someone you can impress with fairy tales.
Okay, those out of the way, I'll start listing positives/negatives as I see fit:
Ostagar
-Cailan was a fool. The whole 'glorious' battle with him and the Grey Wardens holding off the 'tide of evil' was incredibly stupid, and a huge waste of life/resources. Loghain was wise to pull out when he did.
-Duncan told Loghain no Grey Warden secrets. Nothing. Not how to slay an Archdemon. Not why the Grey Wardens are needed. Nothing. As Commander, it was his responsibility to inform the general all essential battle information.
-There are only 2 dozen Grey Wardens. That's just pitiful. Transfers could have been pulled from anywhere BUT Orlais. If Duncan had come clean with Grey Warden secrets and shown respect to Loghains justified suspicion of Orlais, Ostagar could have been a whole different story.
-I don't buy the whole 'Betray his king for power' argument. Not after reading Stolen Throne. But this is something we will get back to.
Back in Denerim
-He declares the Grey Wardens traitors, and assumes the Regency. Depending on the Origin, this can be somewhat understandable, to rather unwise. He had nothing to fear from a Cousland Warden, for instance. I don't care what lies Rendon whispered in his ear.
-Rendon Howe takes control of Highever and Denerim without a challenge. Extremely unwise, even discounting the Cousland Origin. Loghain could have made quite a few more allies if he gave Denerim/Highever to someone else. The nobles would almost certainly be outraged at Howe's presumption, let alone the crimes he committed. Bryce had friends, as I'm sure Urien did.
Mage Tower
-No fault. All Uldred, and the Templars fault really.
Alienage
-No getting around it. That's all on him.
Landsmeet
-I'm rather surprised that Anora has a claim to the throne at all, or that anyone accepts her as Queen again. Marriage means you are closer to the royal family, not part of it. Whatever the case, Loghain undercuts her at every turn, locking her away, or assuming the Regency. That is not a good precedent.
-He's alienated a lot of people at this point. I don't agree with Eamon's plan at all, but he's still a dangerous adversary that needs to be taken care of. So it all depends on the Origin:
Cousland: Loghain might have been a hero, but he's declared the Cousland family traitors, and rewarded Howe for his murder. Loghains' constant interference/defense of Howe, Anoras' stupid plots/betrayals and Howes' lunacy push Cousland over the edge. She's done with the lot of them.
Dwarven Noble/Commoner: Much less personal baggage here. I could see these Origins sparing Loghain, especially a commoner, who is likely not a skilled general, or a Noble, who sees the value of a powerful commander.
Dalish/City Elf: City Elf? Not a chance they will let Loghain walk. The Dalish care little for human politics, though probably just as little for the fate of flat ears. I suspect they will leave it up to Alistair to decide, if they are on good terms.
Mage: Mages have even better education than nobles, but don't get out often. Loghain is very pro mage, and that could be a factor in sparing his life. I don't think a mage would see the Broken Circle incident as his fault at all. It's all on Uldred and the Templars, really. It was a flawed system to begin with.