Well evidence shows that at least his stores tax is much smaller (12% on Epic store vs 30% on Steam). But he has been pretty clearly on the side of "everyone should be able to create whatever software they want on every platform" for a really long time. For example look at his rants against Windows Store and the potential path from it to locking down Windows iOS style (while very unlikely to ever happen is/was a possible path if the Windows Store got really popular)