Here is a link to a Canadian supplier in the GTA with the largest range of adult disposable diapers I could find: http://www.healthwick.ca/
My first order was courier-delivered to my door in two days.
Along with my order for two cases of diapers, I was offered 5 free samples of any diaper product (apparently available with each order).
Discounts are plentiful - including free shipping for next order and for joining their paid focus group.
By comparison testing of multiple products, I believe Abena Abri-Form Air Plus Premium M4 Briefs (43063) to be the most absorbent, even more so than the famed Molicare line: http://www.healthwick.ca/abena-abri-form-air-plus-premium-m4-briefs-43063/.
For day use, Prevail PM Briefs Medium (NTB-012/1) are my favored pick. They are described as overnights, but are discrete for wearing under clothing and are highly absorbent for the convenience of fewer changes: http://www.healthwick.ca/prevail-pm-briefs-medium-ntb-012-1/.
FYI: A month or so earlier, I'd placed an order to b4ns.com, a company that ships out of Montreal, then discovered they'd charged my account in U.S. dollars! I immediately phoned the contact number and successfully had my order cancelled and charge reversed, but only after an ongoing hassle with a guy whose primary language was not English.