wats best primer acid etch or zinc primer ??

as titled lads iv bought zinc primer but was in 2 minds to go for that or the acid etch whats better for keeping the rust at bay???

not sure about the acid etch sure someone will know more but i primed a bit on my bonnet with zinc which was rusty just messing about and has been outside rained on lots since been a good few months now and its still fine was only a light coat to wish i had a garage tho

thanks m8 yeah the garage is great its took me years to get a house with a decent 1