I think Big Team Social is a fantastic addition to Infinite. It is the kind of Action Sack casual social fun playlist that the game has been missing for a long time.
One thing I would change though is how heavily weighted Fiesta is. It has 16 variations in the game list whereas the other modes only have 4 each. I would like to have more variety from match to match in the playlist.
So maybe remove the stockpile and total control variants of Fiesta in the Big Team Social Playlist? That could help give the other modes a chance to breathe and realistically in a big team battle fiesta game, who is playing the objective anyway?