Allied Assault will always be the greatest game of the series (maybe with the exception of Frontline for PS2 and the very first MOH for PS1) and the fact that people still play it online proves that.
That being said, MOH should try to go back to its roots instead of trying to create yet another Call of Duty / Battlefield hybrid.
Two founders of Infinity Ward have resigned and started their own developping studio though. Their first project (most likely a futuristic FPS) will be released through EA.
Every mohaa after AA was god awful, I played the last mohaa and it's some wonky rip off from cod, you can't call it classic mohaa anymore. You might aswell play the proper version of it (cod4) altho I wouldnt recommend that if you don't have 5 commited people (incase you want to go competitive) but the game is pretty good still. I might get the new counter-strike and just heard about shootmania but haven't checked it out yet.