Maybe we should take parts of different systems we’ve seen over the years and put them together.
Just an idea I had was to keep the credit system of Reach, but to have a win count (like exp from Halo 3). So, you will rank up through enlisted ranks (Private, Sergeant, etc.) with earning credits, but to get through officer ranks (Captain, Major, etc), you would need to both earn credits and win some games in multiplayer matchmaking. This way, it won’t be as hard to rank up as in Halo 3. Of course, there may not be as many ranks as in Halo: Reach, since it was a little easier to rank up in that game.
Also, maybe there could be something like a BPR (Battle Proficiency Rating) attached to the player in the game so that other people know their general skill.
What do you think? It was just a thought.