As somebody who has just started getting into CS:GO, I would really like something on the same competitive scale. Halo has always been very competitive, but CS:GO has something about it that just makes it feel a lot more competitive. This could be for many reasons from map design to a much more punishing ranking system.
I also did not get a chance to play the beta, but breakout seems the most interesting so far to me that has seemed to get mixed reactions. One way I think it could draw more players in is by making it even more competitive and the very nature of breakout makes it seem many competitive features from CS:GO could fit in nicely.
First, I would like to see more enclosed maps with specific paths, which I am sure will happen as the current maps were just in the beta. More streamlined maps can make for more strategic gameplay. Even if they are only forge maps, like the ones in the beta.
Require gamechat. One of the most bothersome things in games that require call-outs is when people do not have mics ,it puts your team at a big disadvantage. Some people may not like to talk in gamechat, fine, but do not allow party chat. Spartan chatter helps fix this problem, but nothing is better than real people telling you where the enemy is located.
Punish quitters, allow team kicking. Something I think should be in all competitive playlists, punish quitters with a temporary ban and allow team kicking. Team kicking is very helpful at getting rid of trolls and sometimes somebody who is just not helping your team. Although there should be restrictions to prevent troll kicking, for example if someone is going 2-10 and have a betrayal, allow the team kick.
One more thing I am a bit on the fence about is grenades. I could see flash grenades and smoke grenades working great with breakout. They allow for a lot more tactical gameplay. They would be pretty helpful outside of breakout as well, especially the flash bang. Sort of like the flash ball(?) in halo 3.
Just some quick ideas I had, feedback and suggestions would be appreciated.