I'm having a hard time deciding which game I should get:

Mario Kart DS or Pokemon Platinum. I have Mario Kart Wii already and I also already have Pokemon Pearl. I'm not sure which to choose but the one I do choose will be picked up on Apr. 5th when I get my new Nintendo DSi

Or it would helpful if you could reccomend a completely different game. Thanks in advanced :D

Both are very good games. I would say Mario kart DS because Platinum, while it has some new bells and whistles isn't really worth it if you've put the hours and effort into Pearl/Diamond. MKDS would be a safe bet. It should be cheaper too what with being out for a number of years.

There are plenty of other good games though so don't limit yourself. Legend of Zelda Phantom Hourglass, Fire Emblem: Shadow Dragon, Animal Crossing: Wild World, DK: Jungle Climber & Yoshi's Island DS are also well worth getting into. Don't be afraid to try out some of the 'Touch Generation' titles as well, like Big Brain Academy & Clubhouse Games (also known as 42-all time classics).

get gta china town wars

Seconded. That's a dam fine game.

best non nintendo game on ds

MKDS is clearly the best choice

since the pokemon game is not that new