2014 because Danganronpa 2 Goodbye Despair.

Tales of and Neptunia are a nice bonus tho.

But Totori is better than Rorona.  Boom!

(Seriously though, I tried to do the list so the first game in a series was the representative one, hence no DanganRonpa or SAO in 2015's list, although obviously exceptions such as Persona 4 Golden/Dancing All Night.  Unfortunately, using those rules, Totori was first.  Also I think it sold the best if PSN ratings are anything to go by :P)

Demon Gaze, Blazblue Chronophantasma, Akiba's trip made 2014 a great year for me.. But what make it even greater is that I have a lot of games to play from that Year too. Two Danganronpa, Disgaea 4, Some Neptunias, and some pretty neat atelier games...SAO, Ragnarok Ae, SS Delta.. and more..

2015, so far, have been great on jRPG side too, with more neptunias and Ateliers, plus some nice dungeon rpg like ToHeart2 Dungeon Travellers 2 and Tokyo Abyss... and then, LOH TiTS2 and TiTF, More SAO, more anime related stuff...

Really, Games keep pilling up on my memory card and on my wishlists...

Even numbered years seem to be the years Vita shines. 

2014 just edges out 2012 for me mainly because we got TWO DanaganRonpa Games (which are my 2nd/3rd favorite Vita games), Freedom Wars, Minecraft, Tales of Hearts R, Akiba's Trip, SAO, The Walking Dead Season 2, Wolf Amoung Us, and Toukiden.

2012 Had the what I consider to be the greatest game ever crafted by mankind, Persona 4 Golden. Plus it had games like LittleBigPlanet, Need For Speed, Gravity Rush, Unit 13, Wipeout 2048, Hot Shots Golf and Playstation All-Stars. If it wasn't for the fact that 2014 had the two DanganRonpa games 2012 would have won easily.

2013 had a lot of lulls but it also had some real gems. Ys: Memories of Celceta completes the Vita Holy Trinity (Persona/DanganRonpa/Ys) and is easily a must play game for anyone. Then there's Killzone, Tearaway, Rayman Legends, Soul Sacrifice, and The Walking Dead Season 1 to round out a solid year.

2015 was OK though it lacked a game to rival the Holy Trinity. I haven't quite finished Steins;Gate but depending on how it ends it could change that because so far it's freaking amazing so far. Trials of Cold Steel still has to come out but I'm fairly confident it's going to be the second best game I'll play this year behind Steins;Gate. Besides that I loved P4DAN, DanganRonpa Another Episode, and Ar no Surge but that it's. All other release have ranged from pretty good (SAO:LS/Oreshika) to meh (the slew of Neptunia spinoffs).

2016 has a legit shot at beating 2013 if localizations continue to flow. 

Vita has games

They're all to evenly match for me to chose.  But I think 2016 will beat them all.  It has all the games you mentioned plus dragon quest builders and dragon quest heroes 2. 

2012

Well as someone who hasn't loved their Vita quite as much as most other people here, I give it to 2012, because of Uncharted, Wipeout and Resistance. While Killzone is probably my favourite game for the system, I liked the early goings of the Vita more. Since then, though, haven't been too enthralled with the lineup.

So far it definitely seems there are two camps, those who bought the Vita early and liked 2012 because of the western support; and those who stuck with the console a little longer and like Japanese games, who enjoyed 2014 because of the sea of stuff we got.

Very interesting reading all the opinions, thanks for contributing!

My favorite year was 2013.
Tearaway, Killzone: Mercenary and Soul Sacrifice are fantastic!!! Definitely my favorite PS Vita games!

My second favorite year was 2012.
Uncharted: Golden Abyss, Need for Speed: Most Wanted and Call of Duty: Black Ops Declassified were all very good games too! And 2012 had so much other big and good games!

2014 was also really nice too with all the Indies and Japanese games. And don't forget Minecraft, I put over 100 hours in this game. Love Minecraft so much!!!

Man I can't wait for 2016, One Piece: Burning Blood, Assassin's Creed: Chronicles and World of Final Fantasy are going to be insane!!!