Typically depending on how you view power and decency Atredies were the be Machiavellian fear how much they love us, whilst Harkonnen were the love how much they fear us. Atredies weren't being benevolent because it was right they were benevolent because it was useful and possibly more powerful.
At least as I remember it. I haven't read them in ~20 years so I might be misremembering their takes on power but that was my take away.
So you get into the whole is a good thing done for a bad reason, or at least a morally neutral reason still a good thing? I personally know which house I'd rather live under, but we should be clear it wasn't ever intended as a black and white morality story. The movies just don't have the time to devote to the nuances. We didn't have enough time with Leto and Paul to dig into that so we get a more simple good vs bad and a seemingly good man forced to do bad things for a less bad outcome?