Dungeon random match suggestion
One of the most frustrating things for dungeons is to take a team of champs for a particular side, only to be matched with someone who wants to take the same side. I have taken 3 mutants for the skill path only to be paired with someone with also 3 mutants.
In addition to choosing your team, you could also specify which class you want to take (or don't care) and have the pairing algorithm find the right people. That would decrease a lot of frustration.