What are the best(probably) GPU for causal gaming of 2017

That's not 'casual' gaming, that's a list of some of the most demanding games out now. For 1080p start with RX 470/480 or 1060, depending on if you like AMD or Nvidia. Lower cost cards than that are budget level in performance, you can use them for those games but you will have to sacrifice on something, resolution/framerate/settings.
 

GTX 1050 2GB, will I get smoother gameplay? on low-med setting? with i7 7700? or do i need 1060 3gb, med-high?
for 1050 how many fps will i get to low and med, and 1060 med and high?