I like AMD because their price-performance raport is always good, but I've been buying nVidia cards for years now (started around 08 I think).
Whenever I was talking about switching back to AMD cards, my friends started bitching about their AMD cards having sub-par in-game performance (worst than their nvidia equivalent), driver problems etc.
AMD cards are definitely a bitch if it's a laptop. My laptop had a dedicated 7670m which I couldn't even use for half of the applications due to driver/compatibility issues, so it mainly used the shitty integrated Intel card.
AMD cards generally produce a lot of heat and noise and consume a lot of power, but this Sapphire 390 I got can compete with 970 even in this department.
So far no driver issues. It's definitely performing like expected on GTA V.
And it looks like AMD's 300 series will see bigger gains with DirectX12 than nVidia's 900 series.