In terms of importance, I would argue that nothing matches Avenue and Bloor for its cache. There you have the University, the ROM, the Four Seasons, the city's (country's?) most expensive retail strip, a well maintained park, and of course the provincial legislature. It also serves as the de facto epicentre for the TIFF which is probably the only event that puts Toronto on the world stage consistently. This may change when the Festival Tower is finished but I don't believe that King and John will ever be able to pull off the faux-Hollywood thing.
To me this intersection signifies the height of importance in Toronto whereas Yonge and Bloor signifies street meat, filth, homelessness and the hideously monolithic HBC structure.