In terms of customer service I'd say Purolator is your best choice. I prefer them over UPS because with UPS they leave a maximum 3 tags, and then give up trying to catch me when I'm at home during regular business hours. The its up to me to call them to say "Hey don't send my package back to the sender I will pick it up". Purolator tries once and then phones me for same day pick up from their depot, whereas UPS makes me wait another day so they can take it off the delivery truck.
I have nothing but bad things to say about UPS. Almost all of my dealings with them have been negative!