Thank you for posting on this issue. The ranking system for halo has been the biggest reason why I have stuck to halo for the past 10 years and do not spend my hours of gaming on Cod or gears. I liked the divisions in reach for arena but the best has been halo 3s numbered system.
Make the ranking as close to halo 3 and base it on a combination of individual performance and team wins. Put an added emphasis on assists and let the best man win.