After some careful thought, I've decided that Paris-Ancaster is out and Hell of the North is in.
Hell of the North looks like a much more challenging race, with some really committed racers riding some very serious hardware, so I'm not going to have a good time in that respect. Also, it doesn't hurt that it's closer to home. Conversely, it's my understanding that Paris-Ancaster can be an utter shit-show unless you fight your way through to the head of the second-wave. Otherwise you're stomping through a muddy, single-track, traffic jam of single-speeders, tandems and "cool dads" with babes in tow.
Paris-Ancaster is definitely one of my medium term cycling goals, but I'd like to try my legs at some of the other Canadian spring classics and the local weekly MTB races before then. To put it simply, I hate driving and three hours in a car doesn't appeal to me.