For me, it's always been the lack of a power-user-friendly windowing/workspace scheme. You can approximate a tiling window manager using yabai or similar solutions, but it's just not the same thing.
I love using the MacBooks, but the OS just doesn't feel like it was designed for me, and that would be OK, but I have limited alternatives if I want all of the hardware to keep working.
Also, yes, gaming, but that's less important to me.