Advantages of Sleep
- Has a Medium range (100 ft. + 10 ft./level), while Color Spray is a 15 ft. cone. Sleep can be cast from a much safer distance, which is very important for spellcasters.
- Affects creatures in a 10-ft.-radius-burst, covering 12 squares, while Color Spray covers 6 or 7 depending on placement. Depending on circumstances, either spell can be harder or easier to avoid hitting allies with, but Sleep is better at hitting spread-out enemies.
- Sleep's Duration is measured in minutes per CL, Color Spray's duration is measured in rounds. An enemy affected by Sleep is effectively removed from combat, while some enemies affected by Color Spray can return soon and need to be dealt with again.
- Color Spray doesn't render 3+ HD enemies Helpless, while Sleep does it against 1 to 4 HD-creatures.
- Sleep's huge range combined with its long duration makes it good for escaping combat altogether, when a peaceful solution is desired.
Advantages of Color Spray
- The most obvious and possibly the biggest advantage of Color Spray is casting time (1 standard action vs 1 round for sleep).
- You start casting Sleep, enemies understand what you are doing, they aim everything they have at you. You fail a Concentration check, you lose your spell.
- You start casting Sleep, you don't have enemies clustered that perfectly to affect them all as they have already moved.
- Also, you don't have your Move action to reposition if using Sleep. On the other hand, a well-placed Color Spray following your normal move might end the encounter and make you not worry about the range: disabled enemies don't threaten you.
- While Sleep covers a bigger area, it can only easily affect more creatures at first level because it has a total limit on the HD count affected. Once you start facing 2 HD enemies, its effectiveness halves and then Sleep effectively becomes a single-target spell.
- Once your enemies start routinely having 5+ HD, Sleep is completely useless, while Color Spray retains at least some of its effectiveness: at those levels, spending a 1st-level spell to stun an enemy for 1 round is huge.
- Although not all creatures affected by Color Spray are Helpless and open to a coup-de-grace, they are by no means dangerous while affected, and those Blinded are a lot easier to hit.
- Elves are not immune to Color Spray but are immune to Sleep.
- Even after disabling the most dangerous enemy via Sleep, it can be helped by another foe, effectively countering the spell with one Standard action. The same cannot be done with Color Spray.
- Sleep belongs to the Enchantment school, which is among the first two candidates to be banned by Wizards and School Savant Arcanists, while Color Spray belongs to the Illusion school. Some classes don't care, while others would have to expend more resources to make use of Sleep.
- Note, though, that the linked post is about D&D 3.5e rather than Pathfinder and some things have changed. As such, Mind Blank and Protection from Evil are no longer complete immunities to any kind of mind control: Mind Blank was nerfed... to "only" a +8 bonus against mind-affecting spells. Nonetheless, things are still bad — it’s still a school with extremely low diversity (almost every spell is Will-save-or-lose), many creature types are still immune, and Protection From Evil and Mind Blank are still potent protection for the rest.
- A thing to note is that most combats don't last for more than a few rounds, and there might not actually be that big of a difference between spells here: it will very likely be "till the end of combat" in both cases.
Each of the spells can shine or be totally useless in different situations. A group of goblins shooting their ranged weaponry at you and spread thin is one story, 3 elven thugs in a narrow corridor is another one. Some people prefer Sleep at level 1, and Color Spray past that.
