If Minato used it as setting the bar in comparison to Tobi's space/time ninjutsu I'm more than fine with calling it great/elite.so i conclude that we know nothing of the second space time jutsu or how good it is.
Using the feats only argument is a fine stance to take, however, there's a point where hype does > feats. This is one of those cases. Being an elite user of space/time, the greatest suiton user in the history of Naruto and inventing Edo Tensei...that's hype that's equaled by very, very, VERY few.
Using feats only, people like Shikamaru would be ranked above Tobirama..and while I love Shika as much as the next guy, I think we can agree that would be pretty ridiculous.
Also, I'd like to ask, what feats puts Kakashi above Tobirama? What has he done that is superior to the hype Tobirama has received?