If you want more RPGs to come to the Wii, get Tales of Symphonia. If you want more to come to the DS, get one of the DS games. Personally, I say get the Wii game, because I don't have a DS. :)
COD WAW sounds like it's decent and should have better reply value as long as you like multiplayer online. However, I am waiting for the conduit, and will then pick one. I already have MOH2, and COD costs more then the other games mention. I prefer RPG to FPS.
Replay might not be as good for TOS, but should last you 40 hours if you don't race through it, which isn't bad for a $40 game. (Cosidering some PS360 games are $60 for 10 hours).