The Radeon R9 295X2 has by far the highest hash rate (46.0 MH/s) of the GPUs on the market and will cost you $600. It has a power cost per day of about $1.44, a return per day of about $1.61 and a cost per MH/s of $13.04. This gives a return per year of $586.43.
A Radeon R9 HD 7990 will cost you $680. Its power cost per day is lower than the R9 295X2 at $1.08 but its hash rate is significantly lower at 36 MH/s. Its return per day is $1.29 while its cost per MH/s is $18.89, giving it a return per year of $469.40.
The Radeon RX 480 is most arguably the most economical in terms of cost and saving electricity. Its power cost per day is significantly lower than the two that I have mentioned at $0.4320. Its hash rate is 25.0 MH/s, meaning its cost per MH/s is $7.96. This gives a return per day of $1.21 and therefore a return per year of $440.91. Radeon RX 480 will cost you $199.
A Radeon RX 470 has a modest hash rate of 24.0MH/s. Its power cost per day is exactly the same as the Radeon RX 480 at $0.4320. Its cost per MH/s is $9.13, giving it a return per day of $1.15 and a return per year of $418.16. Radeon RX 470 will cost you $219.
