Edmonton is definitely the "Festival City" of Canada. I know it's easy to look at that as just being a cheesy tourism term that really doesn't have much of a real, tangible truth to it. But it's true that for it's size Edmonton definitely punches above it's weight in terms of festivals. Edmonton does not necessarily have one big festival like say the Stampede, or Jazz Fest in Montreal. But a number of pretty big events that basically mean there is always something going on during the summer months, whether it be The Fringe, Folk Fest, Heritage Festival, Street Performers, etc, etc. Not something that you're going to travel to the city for, exclusively to do that thing, but if you're staying for a couple weeks during summer, chances are you can catch at least 2 pretty big festivals.
One area I think Edmonton's festival game can be improved is during the winter. Basically Canoe Volant is the only big winter festival. I think 2-3 new winter festivals would do wonders.
I love Edmonton's food festivals, like Heritage Days (which let's be honest, despite being about cultural diversity in general is mainly about food) and Taste of Edmonton.
A winter food fest would be awesome, maybe a split indoor/outdoor format. Maybe an emphasis on Indigenous cuisine?