Waaayyyyyy too early to tell. The potential is there, I think but I wouldn't have believed halo 2 or 3 would be the powerhouses the became if I would have answered that question in their early months.
This is how I rank it as of right now:
1) Halo MCC - (everything works wonderful for me, just need to add reach and enhance the playlist). Rankings were good. Love the playback value. Will play this for years.
2) Halo 2 - (basically made live / internet play perfect). Love the ranking system and clan ranking system.
3) Halo Reach - Fun series (need this on MCC).
4) Halo 3 - Great addition but I'm not sure about the items
5) Halo CE - It was fun but challenging to move around the big xboxes.
6) Halo Wars - (different game I know but I like this game)
7) Halo 4 - The pistol comeback was amazing but I never like the special abilities.
8) Halo ODST - I like the co-op campaign and multiplayer fire fights. Let's not forget this was an add-on to 3 so it gets points.
9) Halo 5 - No split screen (campaign or co op). Not a huge fan of the scopes or the menus to play. Not many maps. Still a work in progress. When your roommate or your buddy can't play the game with you when they visit you, it sort of defeats the purpose. Also, the radar is a little useless as it's range is too small.