PS3 or PS4 ?

I only have a wiiU console and I was looking to get another one. which one do you guys think that I would get the best run for the money?

PS3 definitely. There's not many games for the PS4 out just now, and it's still quite a sizeable amount of money for the console itself - there are a lot of great titles for the PS3 and it's not too expensive at this point.

Also I moved this to Gen Gaming for you - discussions of this nature belong in there! :)

To my knowledge, the PS4 doesn't have that big of a library yet. A lot of the games you get for it now is also available for the PS3. I have a PS3 at the moment and I've been enjoying it quite a lot for the past couple of weeks. A couple of exclusives at least worth checking out are Hatsune Miku: Project Diva F, The Last of Us, and Metal Gear Solid 4. I wouldn't recommend MGS4 unless you played the older games first, though. If you're lacking an Xbox 360 then there are probably a lot of multiplatforms you'll be able to get with a PS3: Fear 1 & 2, Skyrim (although that's better played on the PC), Darksiders, Assassin's Creed II, Mass Effect, Bayonetta, and Deadpool. You can also get old PS One and PS2 games from the PlayStation Store on PlayStation Network if you don't want to pay extra for a PS3 that's backward compatible with the PS One and PS2.

Edit: Got beat to the first bit.

If you can afford it, go PS4. The growing list of quality retail games is complemented by an already impressive library of digital titles, many of which are free. The system is now hitting its stride with the Destiny beta going on for the next week and a half (I can give you a code) and The Last of Us Remastered coming at the end of the month. Unless you plan on buying 10 retail discs, there's more than enough to keep you occupied until the big holiday lineup starts. And when it does, you'll be all set to play the highest quality versions of those games. The biggest reason, though, is that it's only marginally more expensive than the PS3, due to Sony artificially keeping the price high.

Either way, subscribe to PlayStation Plus, as it adds two free games to your library every month. If you do decide to get a PS3, wait until Gamescom next month, as, historically, Sony has announced their price drops there.