Normally I try to avoid console war stuff nowadays since they just turn into pissing contests with no sign of stopping, but I had to address a few points on this one:
1) You bought a Nintendo system for its media capabilities? Pfhhhhhhhahahahaha. Good God why? That'd be like buying a Prius so you can haul your RV- sure you could do it, but you can clearly tell the car was not made for that purpose. Nintendo is, was, and always will be completely unable to comprehend how certain things in the modern gaming market work, and bless their hearts for trying, but really, if you bought the DSi for media capabilities, you're doing it wrong.
2) Two analog sticks is not a selling point for a handheld system. The only games where having two analog sticks is a major upgrade from using only one are shooters, and there are two problems with that:
a) Logically speaking, touch control would work better than dual-analog, better than a mouse if you didn't even need to drag to actually aim. Both systems have touch controls, point is moot
b) Shooters on a handheld cannot be taken seriously no matter how good the graphics are, because the screen is too small.
You can make the argument that fighters work better with dual-analog too, and I will grant that point.
3) The 3DS's 3D "gimmick" lowers your opinion of Nintendo, but not the PSVita's rear touch-pad? Really? 3D without glasses lowers your opinion - mind you, this is the first time this has ever been made so easily available - but not a touch-pad on the back of your system, where most people tend to rest their hands and may accidentally touch? Really? I'd reappraise your opinions there man, just saying.
4) Which system has games you enjoy more? Assuming you're getting the system for games in the first place, that's your answer for "better system" regardless of any and all other factors. Personally, the 3DS gets my vote for now because I enjoy the one game out that I actually wanted (Ocarina of Time, natch), and am looking forward to many more that are down the pipe - Paper Mario, Star Fox 64, and Smash Bros. to name a few. I have heard no news of any PSVita games that I am looking forward to, so it does not get my vote - when they announce a new Dissidia Final Fantasy or Kingdom Hearts game further on, I'll be game to get the PSVita too, but it will not trump the 3DS, only put it on even footing.
5) PSVita has one major problem with it that I cannot overlook - if you want the 3G version, the plan uses AT&T. Pass. Yes I know I can get a cheaper WiFi version; I'd like the 3G support but I refuse to play any part in a plan involving AT&T. Bonehead move on Sony's part.