Maybe wait for the 50 series, and then get a 40 
Cheaper that way.
Bench-test wise, cores will win, but in daily use VRAM wins hands down.
I don’t know for sure, but I’m pretty sure Nanite isn’t suited to static lighting. You’re fighting the system. Either go all the way and use dynamic lights, Lumen and Nanite. Or, use static lights and LODs.