EDIT: I made another forum post in detail go check that out!
I really want to see the progression system from Halo 3 make a return with a more friendly progression. Ranks in that game had really good meaning and seeing a General in a lobby was a sight to see. In Halo 3, every won match net you 1 EXP. A loss will result in not earning anything and quitting early or getting booted would deduct your EXP by -2. However, the EXP requirements to hit Grade 4s in each rank was pretty high.