Well, AA is a free game, and a relatively simple FPS. Dropteam might be able to attract better players.
Also, AA has some problems because it is played on relatively small maps with fixed missions. One of those problems (a very normal one) is that there are a small number of options to use in each map, and all experienced players know them, so it becomes routine and winning is not decided by tactics (everyone already knows all the viable tactics for every map) but mouse skills. Also, there is some almost-cheating behaviour (not really going outside of what the game allows, but not something that would happen in real life), like the grenade launchers that memorize exactly how they need to aim to get a grenade from their spawn to the enemy spawn in the first five seconds of the game.
As Dropteam will probably have much bigger maps, I guess it would have more variety.