Wait. Wait. Wait!

FREAKING WAIT!

Wait

Wait at least NX reveal, but saying that Wii U has great games, and has support for Wii game also, so definitely you wouldn't make mistake.

Are there games on Wii U you want to play? If so then buy it. But since you're asking for games I guess you haven't really cared about Wii U games so far. In that case if you can wait, then wait.

Wait for the NX announcement which should be in the next months.

Wait my friend. Unless you want to buy old games used on Ebay for the next 3 years, playing catch up... get the NX and start fresh.

I'm going to go against the grain and say don't wait!

Your time as a human being is so limited and you deserve the most out of your life. Patience is something you should regret when trying let yourself indulge, after all your missing out on opportunities really kills you on the inside ...

Get a used WII U since there's NO GUARANTEE that the NX will have pure hardware backwards compatibility or they'll re-release a lot of the AAA titles from the WII U on it ...

I dont think we will see all that many remasters / ports from the Wii U. I think we will see sequels for the most part.
Also I dont think they will go for backwardscompability this time around so I say go for it as well! Lots of great stuff to be played.

I got a Wii U myself about a week ago and I think it's totally worth it! There is a friggin' TON of great games you can't get anywhere else. Yeah yeah, maybe games will get ported to NX, maybe NX has BC, but what does that help you right now? Nothing! You would waste an entire year just with waiting, just think about all the great games you could play in that time instead. So I say go for it, if you have the moneyz.

That being said, a New 3DS is also a great option. Especially if you're into Pokemon, because that's where you will find the main Pokemon Games. Sun and Moon is coming in November! So maybe that's a (cheap) alternative for you.