Based on the way AC has been changing stuff lately, my revised upgrade policy for myself is:
Domestic: buy V or higher so I won't be getting less than 100% Q miles.
Transborder:(except HNL) Who cares, just get the lowest fare since I am going to get 100% Q miles and no meal service anyways. In most cases, it'll just be short haul aircrafts. Not worth the extra for V or higher.
International: Definitely V or higher so I could upgrade for the comfort.