Well, you make up your own mind of course, but please note that it's well documented that Phoronix has a grudge against AMD because AMD doesn't give him freebie cards. He makes no secret of it, and only published very biased benchmarks. Phoronix is a bit of a moron, only use phoronix for links to other articles, not by phoronix lol. Don't believe anyone that says that a card with half the bus width outperforms a card from the same generation with double the bus width, it's just not going to happen.
With nVidia, you don't have the slightest chance of good KMS performance, they'd rather die than open source kernel modules, and nVidia cards suck pretty hard when it comes to OpenCL, because nVidia - again - refuses to comply to the open source standards. Also in terms of scalability, AMD complies to the open source standards for OpenCL and OpenMP, but nVidia doesn't, it has it's own protocol, viciously called OpenACC, because it's not "open" at all, and it just doesn't compile with GCC, so that's a big problem for linux users, it will only compile with LLVM/Clang if you add OpenACC, and that will bring nothing at all, for there is not a single application that actually uses it.
That doesn't mean that you have to stay away from nVidia, if you need lower power usage or really low noise for instance (even though the latest AMD GPU's aren't that bad either in terms of noise) in a really small form factor, nVidia is the way to go. The only desktop nVidia card that I would be interested in though, is the GTX 750Ti in very small form factor. I've had several GTX680's, those were my last high end consumer range nVidia cards, and just like their predecessors (I've used nVidia for years until 2012 because nVidia actually until then always had the best drivers for linux), they developed power supply problems, something I've never had with AMD cards, that have a much beefier power supply arrangement.
Just sharing my experience here, not judging, I still use nVidia cards in laptops where I don't need a lot of compute performance, it's a matter of what works for you, you have to decide yourself. I actually kept using an old 9800GTX because it's the best linux card nVidia has ever made, and it runs great with nouveau, I use it for the host when I PCI bind my AMD card to my Windows kvm guest on a desktop machine. But right now, for desktop linux use, I wouldn't drop any money on an nVidia card to be honest. For a very small form factor HTPC with Windows, I would go for an nVidia half form factor card, most definitely, because silent, low power, and good Windows performance, even though the nVidia experience bloatware sucks just as much as AMD Gaming Evolved crap, and for laptops with discrete graphics, definitely nVidia, but for desktops, I'll take AMD for the moment.