I think you hit the place of diminishing returns with the 1080 video card, maybe even the 1070, and any decent CPU for AH3. I have a 1080 SLI system and the new TitanXP as well, and really the difference when using 1440p or 1080p high end LCD gaming monitors is about zilch with everyone maxed in AH3 offline testing. 1070 does pretty much the same as the 1080 for AH3 in the short time I had a 1070, and that was even before a lot of newer optimized versions of AH3. I think a dream machine specifically for AH3 is any recent decent CPU/MB platform and a 1070. For other games, and future higher res VR systems, sli Titans or 1080ti, a new 35" LCD that will do 144hz or better @4k, newer higher res Oculus Rift 2.0, and custom hotas stuff.
EskimoJoe, great little system, I ran that monitor before the Asus ROG Swift line came out, I had 3 of them for a couple years, and bought my first one the first week they came out. 144hz is IMO the best feature for gaming, better than Gsync, size, and every other "gaming" feature an LCD can have. 144/165+hz makes a massive difference over 60hz with all games, you'll see it right away yourself, and never want to go back. Great monitor for the size and $.