Gamescope is great but the fact that you can set multiple limits and switch between them makes me prefer MangoHUD, even though I also sometimes use gamescope (with Nvidia my experience with it has been a little bit hit or miss).

This is what I have in my MangoHud.conf:

fps_limit_method=late

toggle_fps_limit=Shift_R+slash

show_fps_limit

fps_limit=0,45,60,90,120,240