Color Spray is awful and so is Sleep due to the health limit.
Sacred Flame almost NEVER hits - ugh, so bad. Since it's dex save results in not half damage but NO damage it really kills the usefulness.
Sleep is a great low level spell - it gives you at first level a HP total you can utilize to put as many creatures you want to sleep as long as they fall under that HP total. So if you have a bunch of mobs that are injured but not dead you can just select them all to put them to sleep. It's a notoriously great spell at low levels, and even higher levels if you want to upcast. There is no save to the sleep effect. The strategic synergy is huge.
Color Spray is essentially the same, mobs don't get a save, so if you are dealing with low health mobs that can still output damage and are grouped you can blind them all. The HP total is much higher for Color spray and it can be upcast to great effect.