There was a time when ATI drivers were unreliable but that’s no longer the case. Things have steadily improved ever since they were bought out by AMD (which for the record was eight years ago). Those who would disagree probably haven’t used an AMD card in years.
For applications that use OpenCL there’s no comparison because the low end AMD cards are faster than the high end Nvidia cards and nothing else comes close to the high end AMD cards. The GeForce Titan starts at $1,000 if you can even find one in stock and it’s roughly half as fast as the Radeon R9 290X which is $550 (speaking in terms of OpenCL performance).
The only reason I see for going with a Nvidia card is for applications that require CUDA to function (which isn’t many these days). Mari used to be another reason to buy an Nvidia card because the early versions supported only Nvidia cards but now they support AMD cards as well.
