So ill just go over the things you have mentioned.
GPU: I havent heard any bad things about the 10XX series, but I will say i have heard a bunch of bad stuff about AMD's video cards. Blizz games run better on nvidia.
Ram: I recommend getting atleast 16 gigs, 8 is starting to show its age.
Keyboard: thats all on you buddy lol. Personally im not that picky when it comes to it, I did buy the Razer black widow chroma (i love the customization of the pretty lights lol)
Monitor: I personally like the ultrawides by LG, as far as gsync goes I couldnt really see a difference between having the gsync and not having it. Just make sure its IPS through.
Looking at your current config I would recommend upgrading the SSD 120 hardly holds all the blizzard games now a days. The brand of SSD I recomend is Samsung
Lastly, never mix and match your RAM. Newegg has stupid good deals atleast once a month for it.