Rogue PVE build

I was wondering if there is a good guide somewhere to which bonus’s on items I should keep to create Mythics. Are mythics better than eternal s? Should I try and get one “set” over another? I am clearing lvl 600+ right now with not much issue on epic. I want to try and do it on mythic 3 and I think I need to work on gear I just don’t know where to go for that info. When I search here, there isn’t much specific dtail.

myyhic and eternal why not combine them both