Propellants: Good and Bad
Lighter Fluid: Nothing bad about it except it leaves fumes that can fire after firing.  It leaves no residue.  Good power.
Hair Spray: Good power, bad smell. Will leave a residue that needs to  be cleaned out after every session.
Gasoline: Just plain don't use it. Will cause the glue to break down.
Propane: Excellent power, but extremely dangerous to load, I strongly recommend not using it.  Could blow up gun.