I've never considered SCSU to be a huge rival. Always a good weekend of hockey and generally two really good teams but there isn't that hate like with some other teams. Denver, absolutely! So many crazy games going back to the Paukovich hit on Bina, the brawl at the Ralph, the dasher dance, and some big time hockey games too. Biggest rivalry we kept coming out of the conference realignment. I would even put Duluth over SCSU, there were some pretty big and intense games over the past 10 years; and heated moment (paging Mr. Pionk).
MN is not the same as when it was WCHA, but its still a rivalry, with some bragging rights. Just not the same when you don't play twice a year (at least). Back in the WCHA days I would have put Wisconsin up there too, but that has certainly dissipated.
Omaha doesn't seem like a big rivalry to me as a UND guy, but I think it is a pretty big one for them.