290/290x if you have free electricity ( expect 250w-350w at the wall while dual mining )
rx480 if you can get them cheap

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280x ( 1175mhz core / 1700mhz mem ) hashes around 17mhs ETH + 500mhs SIA

290x ( 1125MHZ core / 1500MHz mem ) hashes around 31mhs ETH + 620mhs SIA

390 are similar to 290x, not worth the extra price

Stop embarrassing yourself Spacemarko. Grab a power meter and measure the load of the miner at the wall socket.

Each R9 380 takes 150W-300W at the wall. That's 450W-900W for the graphics cards + 50W-100W for the rest of the PC.
My guesstimate for power usage of this system at full overclocks is 700W mining Ethereum, 850W mining Ethereum + SIA.

You might want to also check the temperatures of the graphics cards. If you're getting such low profits, the cards a probably throttling down due to heat.
Please tell me that the 3x R9 380 are not inside a single PC case.