Not the one you would guess from a map. Downtown is not in the middle of the city, and the CTrain line you are on beats the compass direction every time.
Downtown Calgary sits immediately south of the Bow, toward the west of the city centre — and because the street grid runs much further south than it does north, that puts it well north of the built city’s midpoint. Equal-sounding distances are not equal. A deep-south address is a longer trip than a far-north one, and a far-east address on Deerfoot behaves differently again.
This is also why the inner ring in every direction commutes well. The communities immediately around downtown — north across the river, west along the Bow, south through the Beltline and Mission, east through Inglewood and Ramsay — are all short trips. The question only gets interesting past that ring.
In order of how much they matter:
Do not pick a side of the city. Pick a line, then drive the actual route on a Tuesday at 7:45am and again at 5:15pm before you write an offer.
Community-level shortlists are on where to live if you work downtown. If the quadrant letters are new to you, start with how Calgary’s quadrant system works.