Any answer you get to a question like this will be entirely opinion based ssince everyone is going to have their own preferences to the hero types in the game. I have a fairly detailed post on the fortnite game guide that goes over the pros and cons of the differerent hero types in fortnite. Read over this and figure out which is the best hero class for you. Whichever one you decide is the best, is the one that you should evolve first.
I will give my 2 cents on it though. For me, i tried to keep 2 heros going. An outlander to use for quests that were not too intense. This let me gather the maximum possible resources that I could. Then for the quests that were a llittle more tough I would use my soldier hero. Since the soldier was the one kicking the asses, I evolved her first. Having a strong outlander didnt to me much good since this class isnt great for battle. Your decision might be different if you dont like the soldier as much as i do, but thats my thoughts on it anyway.