As of right now Tobirama remains hype and nothing more than that. It's hard to judge either shinobi's skills when we know little about what they were like, Hiruzen in his prime and Tobirama in his.
The fact remains that the one fight Tobirama was involved in showed very little of what he can actually do, and what people said he was capable of.
The same can be said about Hiruzen, as sadly he was very old and lost a large amount of his life force and chakra due to age.