Which Config would you choose?

Which computer config would be most efficient (for Resolve & Fusion) of the following 3?

#1- 2013 Mac Pro, D700, 64GB ram, 12 Core CPU

#2- 2017 Lenovo ThinkStation, Dual E5-2630v4 (20 Cores), 64GB ram,
GTX 1080ti

#3- 2017 Asus X299 Prime Deluxe, i9-7900x CPU, 64GB ram, GTX 1080 ti

I would really like advice. I am leaning toward Mac.

Thanks

#3.... FUTURE PROOF

#3.... FUTURE PROOF

Thanks Steve
I'm sure you are right that #3 is good for a longer future.
It would be great to see more opinions.