Unless you are diamond or higher breach because just about nobody looks away from them and you get 3
breach’s flash is objectively better. omens is a near sight. if omen flashes and peeks a close angle he doesn’t have a huge advantage because the enemy can see up to around 7 feet, even though you can’t hear while nearsighted. breach also has 3 flashes to omens 1 nearsight. if flashes are what you want id take breach. but omen has smokes and teleport so they are balanced. preference is based on your playstyle.
i think breach if its a good breach with proper positioning