There are three major cell phone companies in Canada, and their subsidiaries.
Bell Mobility -
Mobility- bell.ca [Solo, Virgin Mobile]
Telus -
TELUS [Koodo]
Rogers Wireless -
http://www.rogers.com [Fido]
Rogers reception is rather spotty if you leave the city and go anywhere out in the country much...in Newfoundland (not a good example, but regardless) Rogers only has coverage in/around the St. John's metro area (pop. ~180,000). Everywhere else, it doesn't work, but Bell and Telus have coverage virtually everywhere. Rogers 3G (for data) is known to be spotty as well and half the time the phone will drop the 3G/HSPA connection and fall back to EDGE.
If you don't want data (ex. internet) on your phone, none of that is relevant, but either way Bell and Telus (who have virtually the same coverage) are far superior to Rogers in that regard.
As for customer service, Bell is abysmal. They will even attempt to upsell you on tech support calls. My data connections were going down fo about 2 weeks and I finally got through to someone at Bell about it (other people in the area were having the same issue) and the first thing the tech support agent asked was if I wanted to purchase a mobile internet stick free on a 3 year contract, then half way through the call he asked if I wanted to upgrade to Fun 20 from 15 because it was much better value... ABYSMAL. Rogers isn't great, but it can't be any worse than Bell, and I've never had a Telus phone but I've heard better things.
In the end, the "big 3" all collide with one another in terms of pricing/plans and you're being severely ripped off either way. I'm about half way through a 3 year contract with Bell Mobility and I can guarantee you that I will be leaving Bell the day my contract expires.
If you're living in Montreal, you could also consider the upcoming Public Mobile. They're promising unlimited talking and texting for $40 per month, but coverage is limited to the Windsor-Quebec City corridor. That's fine though if you live in Montreal... Wind Mobile is launching soon as well and promises better plans and customer service (and they will be well-needed competition in the wireless industry) but they're not licensed to operate in Quebec so you're out of luck there.
I would consider either looking at Virgin Mobile (Bell-owned, but a little better in the customer service department) or waiting for Public Mobile to launch.
You can read more about Public Mobile here,
Public Mobile | Everybody Talk