most coolant is made up of 50/50 mixture of water and organic chemical like organic chemical like ethylene glycol, propylene gylcol or diethylene glycol.
theoretically speaking, pure water has higher thermal conductivity and capacity hence the higher the proportional of water, the better the cooling performance to a certain extend.
unless you live in country with freezing condition, which require organic chemical to lower the coolant freezing point, a coolant that is mainly water is a better choice. boiling point is not much of a problem as the pressure within the radiator will raise the boiling point of water way above your operation temperature. if the temperature manage to go beyond that, it doesn't matter what type of coolant you are using, it will eventually boil as there is insufficient cooling to sustain your engine operation.
in real world performance, there is not much different in performance among coolant as the coolant temperature is controlled by the thermostat to be within operation temperature.
a coolant with majorities water in it might give a slight edge but nothing to shout about. it might also cool your engine slightly faster when there is a need to.