It's Montreal and Toronto. Although, if you are factoring in ownership, both ownership groups are fairly low-key, so the President/GM isn't dealing with insane top-down pressure. But, fanbase and media are nuts. Toronto because its the center of hockey media, has their rights split between both SN and TSN locally, and even the National media is going to skew covering the Leafs because the Golden Horseshoe accounts for about 1/4 of the overall Canadian population, and that reduces closer to 1/3rd of Canada's population when you remove people who consume media in French. To put it in perspective, that is a bigger percentage of Canada's overall population than NYC, LA, Bay Area and Chicago CSA's are of the United States. That's before getting into the Leafs having arguably the largest non-home team fanbase in other Canadian Cities. Now, Toronto is the only Canadian city with other Big 4 professional teams which reduces pressure to an extent as they aren't the only show in town and the percentage of passionate Leafs fans to passionate Oilers or Jets fans in their markets is probably lower (but obviously still significantly more overall).
After those 2 it's probably Winnipeg and Edmonton. But, I don't know how to equate desperate owners like Melnyk or the markets losing money trying to gain market relevency like Panthers and Coyotes into the equation. Leafs and Habs make enough whether they finish 1st or 31st that ownership isn't worried about losing money, in other markets the pressure just from ownership must be ridiculous even if the fans are essentially non-existent.