I think Artix-7 would be the best one/most cost efficient to mine BTC on, Virtex is a bit of overkill, and a lot more expensive.
Zynq would probably be amazing as well though (I think)
It seems to be a lot harder to get bitcoin miners to place and route successfully on Artix-7 than on Kintex-7.
Do you know, is that just because the Artix devices are smaller, or have Xilinx 'cost-optimised' the routing resources in Artix?
The usable chip area of the Artix-7-200T looks like a giant 'H', think of a building signage 'H' as in 'HOSPITAL', with two unusable 'parks' thrown in for good measure, a 'Central Park' and a 'Golden Gate Park'.
As far as I have been told, the usable chip area of the Kintex-7 is a huge rectangle.
Get it?