I lived in Edmonton for a little bit and when I visited Calgary I noticed that the city definitely had a big city attitude that was conspicuously lacking in E-town. Nowadays, Calgary is larger both in feel and in population, but it wasn't too long ago that the roles were reversed. If anything, I think Calgary owes part of its success to Edmontonians having a hick attitude and making a slew of idiotic planning mistakes at a crucial moment in their history when they could have entered the big leagues.
For example, if you ask an Edmontonian why downtown is such a drag (it's basically the most American of the big Canadian city downtowns, if you don't count Hamilton), they'll tell you that it's because they tunnelled the LRT using cut and cover methods and, during the three years that Jasper street was an open pit, all the businesses were killed. They conclude by saying that the LRT tunnel was the worst thing to happen to downtown Edmonton. Can you believe that? It's basically like parents telling their children that higher education closes doors. This sort of backward, provincial thinking; this rejection of worldly ideals was their main culprit - and not an ackowledgement that, just maybe, building the world's largest mall while you're simultaneously demolishing two-thirds of your historic downtown core to build brutalist parking garages was what snuffed the life out of downtown.
More than anything, it's really the attitude of the citizens and city leaders that determines whether a city will really take off. Calgarians have it, and Edmontonians didn't and as a result a clear winner has emerged from what was, until recently, a fairly even sibling rivalry.