Go for Hashirama overall he's the most useful of the 3 hokages you have, manual barrier with immobilize, plus buffs for konoha ninjas, why not?

Hokage minato is meh imo, and it will be bad later on, compared to his jonin version which is 100 times better

Hiruzen is a tactical ninja, you need to use him very carefully, on a plus side, he has an amazing earth damaging standard, but other than that, i dont see him effectively being good later on.