I found Batman the best skirmish game
imo. The resins are cheaper, rules are free, cards are available for all and the balance is there too
imo, you could pick any minis and put them into a team (following the usual legal requirements of course) and even the most 'casual' list can still put up against the most 'competitive' as the game rewards player skill more than list creation, which I find is very hard to do never mind on a superhero scale where people will be bias towards certain characters.