I want pretty much everything @Greboth said.
For me they need to sort out the connection. It's been piss poor for years. I've played HC in COD since BO2 because of the poor connections, but this leads to issues with matchmaking when the player base drops.
Will decent dedicated servers fix this? At the moment the servers they do use run at 10 or 20hz. Which is a joke for a fast paced shooter.
As Greboth said they should give options for matchmaking where you can select "local only" like in BO1. I'd rather wait a minute to get into a game if it means the connection is spot on.
Maps need to be 3 lane design. The maps in Infinite Warfare are fucking awful and Sledgehammer need to avoid this. But saying that the maps in AW were actually pretty decent.
And they need to not have QSing. MW;R is virtually unplayable in some lobbies because of fucking QSing. Make snipers effective but also need skill to use. Nobody should be able to run around with a weapon that's a OHK at any range.