I've played Drakengard and Nier. I agree that Drakengard is a bit dated. It is still a good story though. (A little disturbing, but in a cool way).
I liked nier a lot. Especially on my second playthrough. I won't spoil it, but the game will definitely be a different experience the second time. So both very good games, though you wil notice their age. Oh! and i am feeling some hype for Drakengard 3. But we'll see.