Well the first 8th gen console I bought was the OUYA. The less said about that thing, the better.
Last year I built a new gaming PC, the first new build since 2007. AMD FX 8350 Watercooled., Nvidia GTX 770, 8GB 2100MHZ DDR3 RAM.
The first game I played through on this new system was Wolfenstein The New Order. This game felt like a hark back to shooters of the 90s with the handling refinements of today. The whole story and world built around it was cleverly simple. The gameplay was nothing innovative, but a brilliant example of old conventions applied effectively.
I have since finishing this been dabbling with a few other new gen games like Far Cry 4, Alien Isolation, and Shadow of Mordor. All of these have been great fun and my biggest struggle is choosing which to focus my attention on. I've also been enjoying some indie titles, most notable Distance, Toxikk and A Story About My Uncle. Two of those games are early access, and they've restored my faith in the whole early access system (despite all the crap on there).
If you're a fan of Unreal Tournament or Quake, then I highly recommend Toxikk.
I also bought a Wii U earlier this year. The first game I got for it was Mario Kart 8. It's my go-to game for a quick muck about. It's beautiful, fun, and the DLC is fantastic too. I've also been playing a fair bit of Mario platforming, NSMBU and NSLU, and SM3D World. Super Mario 3D World is a bit too easy at times, but collecting the green stars and stamps adds the necessary challenge. The New SMB/SLU games are definitely more challenging.
Sonic Lost World made it onto my collection. Honestly... it's not bad. It's not amazing either. I much prefer Generations.
Super Smash Bros U has beaten Melee off the top spot for me. Melee's gameplay in HD with a larger character roster at 60fps. I'm very happy with that.
Finally, ZombiU. This particularly surprised me as I saw it in a bargain bin for £8. It's the most atmospheric game I have played in years. The unique game mechanic (which I don't want to give away as it's a nice surprise) is very clever.
I almost forgot handhelds. My 3DS goes everywhere with me. My most played game on it is Final Fantasy Theatrhythm Curtain Call. If you have a 3DS and a spare £15, it's so worth it. I haven't enjoyed a rhythm game this much since Gitaroo Man.
Bit of an observation, currently if you have either a PC, Xbone or PS4, it's not worth owning more than 1 of these three. Neither of the three have enough exclusives in my opinion to warrant owning more than one, at least not yet.