I'm mining with a Sapphire r9 290x and a Powercolor Radeon HD 7850. Getting 500Kh/s from the r9 and about 100 Kh/s from the 7850. Here are the settings for each:

Sapphire R9 290x
"auto-fan" : true,
"gpu-fan" : "40-100",
"temp-cutoff" : "95",
"temp-overheat" : "95",
"temp-target" : "88",
"intensity" : "20",
"vectors" : "1",
"worksize" : "512",
"lookup-gap" : "2",
"thread-concurrency" : "24550",
"shaders" : "0",
"gpu-engine" : "1000-1000",
"gpu-memclock" : "1500",
"gpu-powertune" : "0,20"

Radeon HD 7850
"auto-fan" : true,
"gpu-fan" : "40-100",
"temp-cutoff" : "95",
"temp-overheat" : "85",
"temp-target" : "75",
"intensity" : "11",
"vectors" : "1",
"worksize" : "256",
"lookup-gap" : "0",
"thread-concurrency" : "6144",
"shaders" : "0",
"gpu-engine" : "1000-1000",
"gpu-memclock" : "1250",
"gpu-powertune" : "0"


Still working on the 7850. Will update if I find something better.