I don't think they send the majority of recruits to any one place. They're usually sent to air bases to get some exposure and where they get sent depends on a number of things. Recruits can and do get sent to Trenton and North Bay, but also other places such as Greenwood, Bagotville, Winnipeg, Moose Jaw, Cold Lake, and Comox, among others.
Do bear in mind that you might get put in Trenton or North Bay for your pre-QL3 time, but you can just as easily get posted across the country after QL3, or vice-versa.