Colour me surprised, I was expecting the iPad or the 3DS to win this. That said, I do agree actually agree with them. The Vita is by far my favourite handheld gaming device, and I say that as someone who owns (or has owned) a 3DS XL, Vita OG, Vita Slim, iPad Air and several high-end smartphones.
I do prefer the slim edition though.
http://www.theverge.com/2014/12/4/7332945/best-portable-console-gaming

Video games are welcome at the table of popular art, alongside movies, music, and television. Home consoles get a lot of attention, but portable gaming has done the heavy lifting when it comes to expanding the reach and acceptance of the medium.
The road to ubiquity began with the peculiar rise of the Game Boy. An outdated piece of hardware upon its release in 1989, Nintendo would nonetheless sell over 115 million Game Boys and Game Boy Colors. Nintendo advertised the portable as a hobby device not just for the kids, but for the family. Countless adults lots entire nights to Zelda and Tetris.
Since the late 2000s, smartphones have spread across the world at a rate that flounders Nintendo’s hardware. Millions of people who never owned a home or mobile game console now do, and the thousands of good, bad, and somewhere in between smartphone games have become a preferred distraction for grown-ups passing a long commute or a quick smoke break.