After playing the Beta I have to say I enjoyed it heavily. While playing it I couldnt help but feel a game mode similar to League Of Legends ARAM or Smite's Arena would work really well with this game. It might just be me but I'd love to see something similar put into the game.
If the playerbase allows for it, I'd be all for a bunch of new modes. I agree that a Payload match would be fun, but I think the biggest priority should be making some adjustments to Core Collection. (Not even sure that's the name of it.)