It varies, I don't necessarily have a fav at the moment, I like to mix it up time to time. or go for whats on sale.
Right now on my shelf I have Formula Shell, Havoline, Penzoil Ultra,Napa Synthetic, Durablend, Maxlife QSUD, Rotella in regular 10w30 and t5, and also T6.
With some odds and ends of Mystik 10w30, and some Resolute