Both are excellent so I don't want to sound like I'm saying Max is overrated because he isn't but IMHO Charles is better.
Charles faced a variety of different style match-ups and displayed a much more well-rounded skill-set than Max who would have struggled if he faced a wrestler IMO.
The Aldo wins were legit and Aldo was still in his prime but I think that Max was a very bad match-up for Aldo (who always struggled with his cardio) and that this led to a bit of an overreaction with everyone suddenly pushing Max as the new FW GOAT when in reality he, like many others who reach the top, was a defending champion but not actually the best there ever was.
Ortega is a complete fraud and has lost more rounds than he's won in the UFC (even in his wins) and really who else is there that stands out that much who isn't a striker? Lamas? Good fighter but not exactly of the calibre Charles has been facing.
Max has the better chin, is a better volume striker, and has a slight cardio edge (wouldn't matter at 155) but IMO Charles is clearly the better finisher, the better offensive grappler, and has beaten better competition. He has the edge for me