I like them both. I don't do "like one more than another". I like things based on what they do. I like systems based on what they do and the games they have. I like the 3DS, most specifically, for KH3D. And I like the Vita specifically for P4G, although I don't have it yet.
Mai waifu: http://img62.imageshack.us/img62/3729/maiwaifu.png
I like the 3DS better because its had a steady stream of good titles that keep me coming back to it, and in general the 1st party titles are more fun than Sony's. Not saying that Sony has no good games for their console, its just that they haven't had a good one in a while. I bought Uncharted, HSG, Rayman, MVC, Wipeout, and MK within the first two months of getting my Vita, but I haven't bought anything for it since that wasn't PSP or PS1 classic. The only games I've been playing on it for the past 3 months have been old TRs, Resident Evils, and Tekken 2/6. When the Vita gets a few more high profile releases that don't turn out to be mediocre or bad (AC, BOD), then it'll start to carry more favor with me. But until then, I'll keep playing in the larger 3DS community online with games like Revelations, Mercenaries, MK7, NSMB2, and Kid Icarus.
Note, I'm not nor have I ever been a fanboy of any console, I'm just stating an opinion based on what I think about both my consoles. My opinion may differ from yours, but don't try to start an argument or insult me, because in my eyes, the second someone uses the words hardcore, rehash, fanboy, or kiddy in an argument they've instantly lost it.
One of the proud people that still plays Mirror's Edge to this day. Not changing my sig until DICE officially announces Mirror's Edge 2
I think that price on the console and memory cards adds a lot on why one is preferred over the other. Also getting into the market first helps a lot. What I'm worried though is that now that 3ds sells fine, Nintendo is focusing all it's resources on Wii U instead, the lack of a great AAA title for 3ds this christmas speaks volumes on the shift of attention from Nintendo, and we don't know anything of Zelda, Metroid, etc for 3ds. which is a big letdown.
While the Vita has stronger technology insinuating it has more "quality titles" is kinda subjective. To me the current 3DS library is better than the Vita's. Although, the Vita has games I adore like Disgaea 3, Silent Hill and P4G.
Honestly people want both, it's silly to restrict yourself to a single system.
Official Wood Elf Druid of the NDF and KDF "Well, I dont have any friends." - VeghEsther