Originally Posted by rusasus
I'm looking for just highest gaming performance because I can get an open box 7970 for 290$
Well the highest performance would definitely be the 7970 crossfire option. Even better yet 7970 tri fire with a 7990 + 7970. Trifire would be about equal to R9 290x crossfire or Titan SLI. However, at that point you will have to worry about any potential multi GPU issues that may come up, and whether the games you play are supported by crossfire or not.
With the above said, and how tempting 7970 crossfire / trifire is..... I'd still opt for the single stronger GPU. So I'd still vote R9 290x. I would vote the Titan with that 290x, but the price tag on the Titan is ridiculous.