It comes down to diving 4 or 5 times a day or diving twice with the night life of Cozumel.
Both are excellent trips and I’ve done both the Bahamas and Cozumel many times, hopefully you do too!
One note on CZM, those prices on the cabs are for the cab, not per person. BlueXTAsea is always complaining that cabs won’t pick up locals because Americans hand the driver $5 bucks each and he drives off smiling ear to ear :)