Accumlative achievements are weak. Basically based on a players playtime, the more playtime the more achievements gained by that player.

Would rather see stuff based on a players skill such as something like:
Solo any level 50 faction leve
Defeat any SH boss with no more than 4 members in your party
Defeat Ifrit with a party where at least 1 of each DoW and 1 of each DoM class is present within the party

Things like this seem better and adds more to the game. Even though it would be easy to cheat these examples above stuff like this trumps achievements like kill 100k enemies and finish 10 leves.