Went to Coz twice last year, did the Peter Hughes Belize boat in May and in July spent a week diving in Sharm with the Red Sea Shadow.
Of the three, the Red Sea tops my list by a wide margin. Certainly more color (fish and coral) underwater, I suspect thanks to the full sun which is an everyday occurrence.
And the good thing for us less experienced divers is the best diving is between 12 and 35 ft. And if you are not going deep, you will extend your down time.
I remember once on a wall near Tiran Island we went deep hoping to see hammerheads. Didn't see any of the big guys and to this day, regret not staying above 30 ft because the reef was just incredible.
While we did not snorkel, the tops of some of the reefs we visited were less then 10 ft and just full of sea life.