Varies from gen to gen for me. 10 years ago (I'm 20 now), I would have said consoles. I liked the GBA (LOVED Pokemon), but I absolutely loved the GameCube, still have more than 50 games for it. Today however, I prefer the handhelds. I've moved away from console games a bit, sadly. Pikmin 3 is the only game on the Wii U I can say that I've loved, while that list is huge for the 3DS.

Handheld. It's the place where most of Nintendo's effort has been this gen

The Wii U library is a lot better than the 3DS, so easy answer.

If it wasn't for the Zelda games I'd regret I ever bought the 3DS. Most of the games are pretty terrible tbh.

I never finished Pokémon ORAS, Bravely Default, Luigi's Mansion: Dark Moon because they were either so boring or infuriating that I rage quit them. That's 3 out of 8 games I own for it.

The ones I finished:

OoT 3D: good game, but overrated

MM 3D: amazing game

ALBW: amazing game, shitty artstyle

Pokémon X: had fun with it, but I'm tired of Pokémon after this one

FE: A: ugly graphics (practically PS1 quality), bland/boring story and decent gameplay (but very repetitive)

I think I might be more into consoles... but I had gameboy, gameboy color, ds lite and 3ds and I enjoyed them A LOT being the 3ds the least played of them all.

On the other hand I had super nes, wii and wii u and I played nes and gamecube at friends or family.

The only nintendo console I have never played is N64. Nobody I knew had it and I would have never bought it (wasnt a big fan of 3d graphics back then).

Pretty much this for me, too. With the exception of GBA. Once I got that baby in 2009 (I was late to the party), I played the crap out of it non-stop. I remember my original GB fondly and played that much more than my NES at the time.

As far as current generations go, I really enjoyed my Wii and Wii U, but I've found many more games to get into on DS and especially, 3DS. The library for those two are so diverse and enormous that it's hard to compare them to the console libraries.  

Hmmm, maybe in the end, it really is handhelds for me.