I always saw a lot of underlying scumbag with Michael. He wanted to be a family man and all that garbage, but everything Trevor said about him was right. I never felt that he regretted what happened all those years ago. Even when trying to make amends with Trevor and explain himself, he never seemed genuine, he just wanted to keep Trevor from putting a bullet in him, which anyone who understands Trevor knows that it was never going to happen anyway. There are a few major spoiler moments that I won't go into, because describing them would be a lot of typing and I don't feel like using spoiler tags, but Michael just seems like an asshole to me, even when he's trying his hardest to do right by his family.
Trevor does a lot of horrible things (by normal standards. I'm cool with it), but he's honest about it. He's a genuine guy, what you see is what you get, alongside an insane level of undying loyalty that's hard to find in this day and age. Anyone who didn't like Trevor wasn't paying close enough attention to his personality. He might punch you in the face, but he would never stab you in the back. I can't think of a single character in GTA history I would rather have at my side when the SWAT team or someone's private army comes to play.