I'm looking for a gpu less than $200 on eBay to put into my build. My future plan is to run two of them. I've found R9 290s, GTX 680s, and GTX 770s for around that price. For those interested here are my (eventual, as I'm not done) specs:
2x Xeon X5670s
48GB DDR3 1333 mhz ECC buffered
1200w PSU
Before anyone asks why the build is based off of the LGA 1366 socket, I'd like to say that dual X5670s perform better at stock clicks than an i7 4690X in most tasks. On top of that I can get two for literally $250ish. I'm not an overclocker and as such I think I'd benefit most from the 770/680 gpus, but I'm unsure. 48gb of RAM is a little overkill... I know, but it will be more future proof.
I hate to question anyone, but multithreaded tasks (a lot of what I do) will perform better on dual X5670s than it will on an i7 4960X. More threads isn't necessarily better, but for what I do the extra threads will provide a benefit. I constantly compile thomgs, extract things, edit things, have tons of tabs open in Firefox, create media, and yes I occasionally do boot up Fallout New Vegas, and a few other Bethesda/Source titles. I've already invested $150 on a motherboard, a case, and in the end I don't want to be out any more than $600-750 on my workhorse. I will be running Linux, and I will be using virtualization for numerous tasks justifying the number of threads over something like a 4960X. That CPU itself is more than the finished product. And to those who say Xeons are horrible for gaming, I have this to say; I had a Dell Precision 490 with dual Xeon 5160s, and an R9 280X and no bottlenecks were present.
For Linux and virtualization it depends on how you want to do things. If you're ok with proprietary video drivers, Nvidia does those better than AMD. For open source, AMD is way ahead. If you plan to do virtualization with GPU passthrough, AMD is about the only choice.
All of that aside, the 290 is the fastest of the ones you've found, by 25-30%, but I don't know how the Linux support is for Hawaii these days. Last I heard, the open source driver didn't work well with 290s. You could save some money and find a 7970 or 280X (same thing), which perform similarly to a 680/770 and are better supported by the open source driver.