Cloth because cooler in the summer and warmer in the winter. Here in Nevada sit on leather only one time with short pants in 100+ degrees and you'll belive in cloth.
My 2011 had cloth and I was constantly getting static shocks from it. I hot some Roush take offs and swapped out for leather and loved it.
Fast forward to my 2017. It was the wheel and interior package that has cloth seat with the embroidered mustang logo and they're comfortable as anything with no static.