I disagree with the A-listers being better for world-building. It makes the world seem a bit shallow when everything is Superman, Batman, Wonder Woman and the League. Adding the Global Guardians to the pool doesn't deepen it that much, but it does give the idea that there's more going on than the big names.

One of the Jacks O'Lantern was a villain for a while, working for the Queen Bee. The two main ones are good guys, though.