For Wii game recommendations: (Ready thyself, this is a long list, pick the kind of games that interest you)

Mario Galaxy
Mario Galaxy 2
The Legend of Zelda: Skyward Sword
Legend of Zelda: Twilight Princess
Metroid Prime 3
Donkey Kong Country Returns
Sin & Punishment: Star Successor
Xenoblade Chronicles
Monster Hunter Tri
Resident Evil 4
Project Zero 2: Wii Edition
Fatal Frame 4
Rayman Origins
Okami
Tatsunoko vs Capcom
Little King's Story
Kirby's Epic Yarn
New Super Mario Bros. Wii
Mario Kart Wii
No More Heroes
No More Heroes 2
Red Steel 2
Silent Hill: Shattered Memories

Don't listen to this guy, buy the Wonderful 101! :P  Honestly, there's nothing else like it.  It is manic, crazy and unpredictable and quite challenging, if occasionally rough around the edges. My only advice is that if you haven't played any recent Platinum games I would advise watching 1 or 2 videos on Youtube explaining the gameplay mechanics, combos etc.  The game does a really good job of not explaining anything to you and assuming that you can somehow intuit the nuances of the control and gamplay mechanics.

Also I don't consider Pikmin 3 or Rayman optional unless you have a thing against great games and seriously consider checking out some Wii games listed above.

Just because its unique doesn´t mean its good.

No, very true..........but it is :)

Seriously though, there is a demo (still I think) which can help one decide whether it's their cup of tea or not. I fully concede this game is not for everyone.

Features:

MiiVerse

Games:

Super Mario 3D World
Nintendo Land
Legend of Zelda - Wind Waker
Lego City Undercover

Upcoming Exclusive Games that look promising:

Donkey Kong Country - Tropical Freeze
Mario Kart 8
Super Smash Bros U
Monolith's X
Fire Emblem vs. Shin Megami Tensei
Bayonetta 2

This is good advice

After Super Mario 3D World, I think the next games on Wii U that one should consider are Wind Waker, Nintendo Land, and Lego City Undercover

I would recommend Rayman Legends, Assassin's Creed IV, and Splinter Cell Blacklist, but only if you haven't already played those on another platform.

NSMBU
Zombie U
Scribllenauts Unlimited/ Unmasked (the DC one)
Lego City Undercover
Tekken Tag 2 (if you don't already have it)
Pikmin 3
The Wonderful 101
Rayman Legends
WWHD
Deus Ex: Human Revolution
Super Mario 3D World
Wii Sports Club (eShop)
Mutant Mudds (eShop)


Just for starters.

The best games you can get on the Wii U are Super Mario 3d World and Rayman Legends, 2 of the best 10 games of last year.
Rayman Legends was originally made for the Wii U, with the gamepad in mind, even if you can play it in another console this is the best version.

The other 2 Nintendo titles I recommend are The Wonderful 101 and Pikmin 3.

Along with Rayman Legends, the other 2 excellent ports the Wii U has are Tekken Tag tournament 2, and Deus Ex: Human Revolution (Director's cut).

Cod and Asscreed are probably better on other consoles.

Wonderful 101 is the best game I played last year (yes, even over Mario 3D World) and one of a small handful of games that had me cackling with laughter as I played it.

Personally I would get the Wii U first, then look at the PS4 later.  The reason being that Wii U is cheaper, further along in development and weaker.  So you could enjoy Wii U and its (currently) deeper library, spend less money, and then have another upgrade experience a year or two down the road with PS4 when its good games come along that start pushing the system.  I did that last gen with Wii and XB360... and I saved a lot of money when 360 went down in price.

If you haven't played Mario since NES you really need to pick up 3DWorld.  For me, it's the best true Mario game since SMB3.  It's almost like a direct 3D sequel to that game, with classic Mario gameplay mixed with great graphical and gameplay innovations.  Mario Galaxy is great too, but it's very different game - almost like a different series than traditional NES/SNES Mario games, and not just because it's in 3D.  They have similarities in presentation, however, since they are both done by Nintendo's best team in Tokyo.