I would take a PSP and MGS: Portable Ops over a DS and any game on it any day of the week. Tactics, Valkyrie Profile, and some of the others mentioned here would just be icing on the cake. And before any of the DS fanboys have a stroke, I've played the DS extensively (my mom and my sister each have one) and the best thing it ever did was run my various FF Advance titles. Granted, Pheonix Wright was fun, but when you've played it once, you'll never need to play it again.