I would go for GTX1060 3GB and mine Equihash (290+ per card)

Or go for RX570 4GB to mine Ethash (28+ per card)

And go for 6x rigs, because 12+ can be unstable

Something like this:

For 1060

G3930 + 4GB DDR4 + Gigabyte H110 D3A + 850W bronze PSU or something gold which have 6x PCIe

For RX570

G3930 + 4GB DDR4 + Gigabyte H110 D3A + 1200W gold/platinum with 6x PCIe