Okay, what the heck?
Bowser is at least a good dad. Of all the "evil" dads in fiction he's definitely like, top of the list for me.
As far as morality debates go, currently our most evil character in my opinion is Ridley. If Porky was here he'd probably be up there with Ridley cause good lord are they just ungodly evil. They're not even forced to he the incarnation of evil like Ganon, nor do they have an iota of good in them. They just want death, destruction, and to demoralize anyone who may be so lucky to be spared from their wrath of pain.
Bowser actually had morals. Many games have showed that even he thinks certain evils are unspeakable and beyond him, and it rings true. Of all the evil characters, I'd say he's at the bottom of the list. Even K. Rool is higher just because he went insane with spite at the thought of some monkeys beating him and is perfectly willing to kill, where Bowser has never done so nor has he tortured anyone. His punishments are just being left in isolation in his dungeon and maybe a beating at best. His tyrannical monarchy is bad, but in his wars and conquests, no one has died to my knowledge. He is a forgiving and benevolent King to his subjects and a good father to his son for the most part.
But I won't be bias. Bowser has threatened to kill Mario and Luigi and in the Galaxy games, his plan was to destroy and recreate the universe so that he and Peach could rule over a new one together. That is pretty damn despicable. But it's generally outweighed by his softer sides and in contrast to everything else we've seen seems a little uncharacteristic if I'm honest. I can't recall any other instance Bowser wanted to literally kill anyone (other than Mario, of course). Though according to guides, he was also brainwashing/going to mind control the inhabitants of Peach's Castle and the residents of the Painting Worlds to serve under his army, and that's also pretty bad. And even within the context of his plans in Galaxy, he probably didn't really think too much on his plan and figured recreating the universe would mean reviving the exact same residents residing within it before. Cause what good is ruling a universe with nothing to rule over?
But like I said before, these are bad, sure, but he has a softer side to him. The other evil ones haven't shown these glimpses of any sort of good or signs of redemption at all. They are cold-hearted, is what I'd describe them as, which makes them a tier above Bowser for me, and his little gray area makes him really interesting to me along with all that charisma.
I know this was more so a "fans of these characters makes them just as wiling to do those things" or whatever the hell that point was, but I just really wanted to weigh in on this particular aspect of it and explain why Bowser is probably the least evil of the inarguably evil characters.