Hi I'm new, was looking through this thread mainly because I'm particularly interested in this matchup due to my liking of my boo Tobz and I just felt the need to sign up to comment on my view of these 2 Hokage.
First of all I'll be honest and just say that I was slightly bias towards Tobirama, however I think that me and many others just decided to jump the Tobirama hype train this arc and some still on that train from just looking at the comments in this thread. Now personally I too also said Tobirama was superior but I think I just let my bias get the best of me.
At the end of the day when I take all bias out of the equation, look at the facts and feats and think logically, I think it's fair to say that Minato is the overall stronger ninja of the 2. Reason I say this is because Kishimoto is not an idiot and neither am I, without letting my own personal feelings blind me I can see that the author has slightly hinted at who the overall superior one of the 2 is.
Tobirama is a Senju yes but I guess that's not everything. Kishimoto has shown who the faster of the 2 is, he's also shown who has the better space time jutsu and I feel that the chapter where minato entered sage mode kind of sealed the deal to be honest. Anyone who thinks otherwise is just being in denial in my opinion, I don't think it takes a genius to see that there's a slight difference in the two.
Let me just say that I think Minatos sage mode was complete and utter bull crap and he should have never have gotten it (kishi trying to justify this by saying his senjutsu isn't as good isn't good enough for me as he still displayed perfect control and ability to use it), neither should he have gotten the nine tails chakra. Yes I was annoyed that he was given those power ups but I've eventually come to terms with it and I think my fellow Tobirama fans need to do the same. It doesn't make Tobirama any less awesome as he's still a complete and utter badass.
Anyway that's just my view, although I think the poll votes kind of tell the story really

as a Tobirama fan though I really wamted to share my opinion. The op made good points for minato, even though there's a bit more he could have said for Tobirama o still have to agree.
Sorry for some grammar, English isn't my first.