Linux will be the main hurdle bc many games just aren't there.
Nvidia has better proprietary drivers and a 1060 for 1080p gaming or a 1070/80 for higher resolutions is the best option.
CPU is less relevant, if you start with a high clocked i5 you will be fine for the next 5 years so do not get overly concerned with upward compatibility (you will change the socket anyway in 5 years).