Mixed can be better. Rolling With Difficulty has a mixed group of players and it's awesome. Red is an expert on tropes and always knows exactly what the DM is trying to do. Sophia has dice blessed by the gods and always pushes the big red button. Noir has a habit of dropping impassioned monologues that completely change the trajectory of the story. And Wally has absolutely wild builds that let them go up against incredibly powerful enemies.

If the party were all like Red, there wouldn't be much momentum coming from the players. All Sophias, and nobody would actually understand what's going on. All Noirs, and you get the Star Wars prequels. All Wallys, and the party would always play it safe and be boring. But with a mix, everyone shines.