Goats vs sheep as family milk animals?

am planning to get 3 goats or sheep (1 male ,2 females) in order to become self sufficient as far as milk is concerned .i like goats more than sheep but i have been told they can be really destructive . my plan is to keep them in a 10000 m2 olive tree and grape vine plantation so they can eat the grass and herbs that grow under them and save me allot of trouble weeding my area. are there goat breeds that do not destroy trees and shrubs and they rather eat grass or do only sheep stick to grass .what breeds of sheep will do well in a hot country . (do not care about wool just milk)