While I prefer Brain Age's more serious approach (damn, that Kawashima-guy isn't serious I think.), how about add in some games that require you to think too, like Phoenix Wright (oh crap, I think it's hard to find there) and Advance Wars (yes, you need to think and not check Gamefaqs :/ ).
That said, I prefer Brain Age. I always seem to look at BBA as mini-games that aren't that good so I don't pick it up as often as I do with Brain Age.
(But my friends also say that BBA multiplayer is fun stuff.)