Wait why are these all nintendo games?
Might have something to do with the quality.
Anyhoo.
I've played a ton of games and I don't remember when most of them were actually released, so I'm probably overlooking a few.
Top 5 in no order would be:
Disney Infinity 2.0
Like 1.0 but so much improvement.
Hyrule Warriors
I don't like Dynasty Warriors so I had little to no expectations on this. I didn't even want it, the game store just had nothing else of worth in stock and I didn't want to go empty handed. I was pleasantly surprised though.
Shovel Knight
It's the only 'retro styled' game I've come across that actually manages to perfectly capture everything about the old classic NES games it's trying to pay tribute to. It's good enough to not only feel like one of those old games but if it were released back then, it would have probably started an entire franchise with a TV series and 50 sequels along with Mario, Sonic and Megaman.
Kirby Triple Deluxe
It's possibly my favorite Kirby game to date. It's just good.
Smash Bros
Because it's my favorite Smash to date and I don't think I've played anything else released in 2014 that I think deserves to be in an overall top 5.
Honorable mentions to 'Final Fantasy X/X-2 HD' and 'Kingdom Hearts 2.5' because whilst they're fantastic games and among my top 10 of all time
and they were released in 2014, I don't feel that HD remasters and re-releases should ever be included in a 'best of 20XX' list.
They had their chance to be in a top 5 about a decade ago. Time to give new games a chance.