I've always used Semi-Metallics, myself, as I've read more than one article about glazing occurring on some Ceramic pads when they get too hot.
The downside to semi-metallics is they transmit the heat when they start getting really hot into the brake fluid if you have metal pistons in your calipers and can cause brake fade after a while.
I won't touch organics, and the Carbon-Composite is new to me.
From past experience, I find that Semi-metallics grab better than ceramics.
The mushy brakes sounds like there's air caught somewhere, still. I'm not familiar with newer trucks, but on the older ones when they first added ABS, if you didn't purge the dump valve (or if the dump valve failed open), the brakes would be perpetually mushy.
