There are tons of DS-only games, so I don't understand the comparison to consoles, really. Sure, if you are talking about a game that is cross-platform and available on consoles too, I'd probably prefer the console version. Then again I might not seeing how I commute to work on train & bus and have a lot more time for portable gaming then console gaming. However, I tend to shy away from such games in the first place because I figure the DS version will stink in comparison. I tend to stick with games explicitly designed for the DS. Plus, I too like 2D games. Indeed, as far as platformers go, I massively prefer 2D - I want to play a game, not a camera.
Having said all that... my main portable gaming platform these days is my iPod touch. The games are ridiculously inexpensive and there are good ones among the dreck. Plus you can spend massive amounts of time just trying out "Lite" versions and playing free games (and again there are good ones). Also the fact that I always have my iPod with me is a big factor too - my DS doesn't get nearly as much play now. , I on an off again consider selling it, but I haven't quite been able to divorce myself from it. There are games on the DS I love and games I'm looking forward too, such as the new Zelda game.