I would pick NVidia only coz of the program i dont know what name is it i think shadow play or something and you are the streamer and you make gameplays so i think if you want to buy new Card go Nvidia for sure! And at all what a read on the internet Nvidia is better so.. GL
Yeah... ShadowPlay, you can stream and record gameplay with almost 0 impact on performance because it's a separate chip on the nvidia card unlike most other recorder/streamers that will use at least some CPU or GPU.
Well.... when you look at lower price graphics AMD is definitely much better option for you....but if you have a lot .. and i mean a lot of money then you should go for Nvidias graphs bcs they have better performance in game... ( btw i voted for AMD )