My favorite lobby/game mode was onslaught team deathmatch since I was a huge Halo "Big Team Battle" fan. I currently main the game "Planetside 2" and really like large team battles. The onslaught maps felt bad because of the three faction battles. I would really prefer a 10v10 or 12v12 in those maps and I feel like it would "make fps great again". No joke though, that's what is missing currently in the shooting genre. Large (non Battle Royale) maps.

I would prefer even larger maps and it be a persistent open world game mode like how planetside 2 is. But, I completely understand that doesn't seem to be the direction this game is headed. At least big team battles would scratch the itch that only halo can right now.