Hard to give specific recommendations, but at this point generally something NVIDIA GTX 1060, 1070, 1080 or 1080 Ti based, basically depending on how much you want to spend. Above the 1080 Ti and below the 1060 the price/performance curve drops off rapidly.op12no2 wrote: If I was to buy a video card just to train Leela, what would be recommend? I can get it through work; so may as well.
As for the different vendors out there, check some reviews for specific models you can get your hands on. Personally, I prefer a quiet card that's energy efficient over an overclocked one that runs 100Mhz faster, has a bunch of LEDs and is loud. (It adds up quickly with a bunch in my office!)
AMD cards will run fine if you have them lying around, and are well supported by Leela, but not necessarily by other deep learning based things. For that reason it's still hard to recommend them.