Hello... I currently have GTX 760 running in a few machines... Here is a general performance chart for you consideration, http://www.videocardbenchmark.net/video_lookup.php?gpu=GeForce+GTX+760
As right now the people are OverClocking the GTX950... and the GTX 960's are showing a slightly better level of performance with New Generation Powerful GPU's... all depends on your budget and the game you want a lot of Eye candy on B ).
Update: Somehow I'm able to get the NVIDIA K6000, will this fit into my computer? Also please tell me where to look to check if it fits as I might compare more video cards and if it works with my computer