Dog's okay...
Well if you are using Fido, you are using Rogers, as they are pretty much the same company utilizing the same GSM network. (Global Standard for Mobile communication). However, as the GSM network is generally all digital, you don't get as good signal penetration (stay focussed here) as the older analog signals used to. Hence, the interiors generally don't get as good reception as the exteriors. With Fido's expanded network, plus the ability to roam outside of North America, AND to be able to switch phones simply by switching SIM cards (voila - all your contacts gets switched to your new phone AUTOMATICALLY) - I like the dawg. I live partially below ground (not under rocks tho) and I still get signal on my Fido.
Switch to Bell or Telus and you are using an older TDMA (or was it CDMA) system. By the way, I can't remeber what that stands for Code Divided something something... As Telus and Bell phones are often at least Dual Mode types (with at least one analogue frequency) they do have better penetration so you get a more consistent signal indoors. Of course, Telus being the old BC Tel has great western Canada coverage as Fido and Rogers are considered more "National" service providers, resulting in great coverage here. As Bell uses some Telus towers in western canada and Telus uses towers in eastern Canada they generally have good and consisitent coverage.
Which is the best? I have no friggin clue. I get decent service with my Fido and I get billing by the second, so I'm pretty happy.