Based on what we've seen Minato is clearly above Hiruzen too. When the 9 Tails attacked Hiruzen twice needed Minato to bail him out in the face of the Tailed Beast Bomb, while he just stood there with his mouth wide open and an "oh F#$@ expression on his face". Plus he has virtually no feats which even hint at a power equal to Minato.
I had Sasuke ranked in my top 10 the other day, but what we're seeing here is Tobirama just got bumped clearly into the top 10, and is apparently able to do things even the edo's Kabuto summoned could not do, flat out override Edo Tensei (Hanzo managed it for a few moments, Tobirama, Madara and Hashi can apparently out and out break it, and Hiruzen just showed he can't). It's obvious Tobirama is going to get boosted way up the list of most powerful Shinobi, and when the power up is done, I'm not even sure Sasuke will be able to beat him.