I think most people would say slinger 1 but recently I’ve been seeing a lot of favs. Considering the unorthodox style of Mahomes‘ slinger 2 release and how it tends to have a very low trajectory easy for lurking defenders to pick without effort it’s clear the speed of movement and how quickly the motion gets the ball out it’s exactly the sole determining factor for a good release. Still I pick slinger 1 for the ability to hit slants and flat routes in a flash.