@Amr low how do you define "best"? Not trying to be difficult, but it's going to be different for different people depending on what your power cost is and how much you can get the cards sourced for. So maybe answer these follow up q's and we can chime in with some better guidance:
Where are you located?
What's your power cost?
Are you buying a new system or upgrading your GPU in an old one?
@Techman34 Yes, a new system and I want to know what is best and budget open and energy has been cost her account, all you want to know what is the best cards available for mining , where they found it different from VGA to another in terms of power .
well I think I got your point, well if the electricity is cheap like where I live its around 0.021/kwh you are better to go with the r9 390s they hash according to the info in the sites around 29-32MH per card so 6 of them will set you up to 190MHs .
but I dont have the funds to build such a rig I went for dual r9 290x / r9 290 / 3x r7 370 4GB with dual 750w psu still waiting for delivery it will take sometime tho about 2 weeks.
In my opinion, go with Sapphire r9 390 or 290 depending on price. Make sure to get something with at least 2 fans, preferably 3 fans, and a backplate always helps to keep your system cool.
Answers
Yes, a new system and I want to know what is best and budget open and energy has been cost her account, all you want to know what is the best cards available for mining , where they found it different from VGA to another in terms of power .
but I dont have the funds to build such a rig
I went for dual r9 290x / r9 290 / 3x r7 370 4GB with dual 750w psu still waiting for delivery