The main goal is for smooth, full mouthfeel and hop juiciness (not IBU), so higher chloride is the way to go. But you do want some bitterness perception, of course, so moderate sulfate is also good. I typically use 100ppm chloride and 50ppm sulfate and it has worked very well for me. I tend to stay with a 2:1 ratio. I've seen others recommend much higher sulfate, but that's definitely out of place here. Also, keep in mind if Chloride is at or above 100ppm, sulfate should stay BELOW 100 or it will start to create harsh flavors.