The problem with Super15 is that, after going through Super10, Super12 and Super14 and now 15, we have to use a different name every 4 years. That's just weird. SupeRugby is a nice name which doesn't define a specific number of teams and therefore is easier to use.
I sometimes still call it Super14 by mistake. SupeRugby is the best name in my opinion, taking into account some teams probably being added to the competition with Argentina's inclusion in the Tri-Nations in 2012