I feel like Tony often works best when he's whatever the opposite of an anti-hero is. What's a character who's theoretically a good guy, but constantly serves the interests of the bad guys? That's Tony. Just constantly making stupid fucking decisions because he's an egotistical prick. Yeah, he's a 'good guy,' in the sense that he fights alongside the good guys and genuinely wants to be good and do good, but too many of his decisions are motivated by ego which ends up with things like the bad guys gaining control of an army of Iron Man armours that Tony was too full of himself to properly secure or destroy.
Tony is basically a built-in foil for the Avengers that they can never defeat because he's ostensibly on their side. And, in this day and age, I think that's the best position to put a 'good guy billionaire' into; a bumbling, arrogant dickhead too high on his own farts to see how much damage he's doing.