Minato gives you an edge over others and can help in beating some one stronger than you too, so i would go with minato if i were you. He works really well with fire main

but just out of curiosity, which event is this that gives wishing bags?

He's referring to the Hokage Optional Gift Pack in the Total Recharge Rebate event i think

Hashirama is still great and probably the strongest between all of them. He is great in 9Tails, ranked, GNW and time-space (due to the lackness of interruptions and overall bad IA, but this is a double edge sword).

Tobirama is pretty meh, probably the worst Hokage atm. His mystery damage isn't great and his blind passive is just bad. You c*e him in ranked or GNW... but he will be outclassed in both of them.

Sarutobi is good. A good meatshield clone, hard hitting mystery and his shiki fuin is just good (except against susanoo sasuke and tendo...). You can have fun with him + danzo/jigokudo/serpent kabuto spamming his passive to kill everyone. No chase and this is bad.

Minato is the true meaning of RNG. Hard hitting mystery, but you need people tagged (hello root/heals/debuff immunity), a very strong auto (with the extra RNG tag action) but no chase.

Overall, the most usefull is still hashirama, followed by minato/sarutobi and tobirama is here just for collection purpose.

thanks for the opinions guys!