Played through twice as a Cousland in different roles among others. As the Idealist, I couldn't forgive the dinfinative act of betrayal at Ostagar, Off with his head.
As the realist with royal ambitions of his own, I spared him, married his daughter and had the benefit of his ironic cameo in awakening.
Since then I never hesitate to kill him and put Alistair on the throne. It's not because I dislike Loghain, it's because I despise his coniving daughter.
Also, like him or not, you got to admire the fact that in the end, he looks you dead in the eye and accepts his fate calmly, this was no comman man. Much better than Alistair's tantrum and guilt trip one feels for not avenging the betrayal.
And for the record on the Howe comments, as a Cousland survivor, even if Howe had had a Warden join option, he would of died, so strong was that feeling, the first time I played awakening, Nathan went to the gallows simply for the fact he was related. I still enjoyed killing Rendon Howe even on my other characters, even though they had no real reason to hate him (Well my alienage elves probably would not of liked him). It was the one instance in the whole game that I regret not having mmo style emotes to really express how I felt about him.