I think that Koodo (Telus / Bell networks) are extremely good. There's very few places that other carriers would be objectively better for coverage. At the end of the day you would have to try for yourself in the places you are. You can let us know the locations or ask around with people you know to see how they think the coverage is.
It's very good as it's run off Telus/Bell towers. I can only speak for how it is in BC. The only other provider that has its own towers is Rogers(and its flanker brands). Nowhere near as good as Telus coverage. Rogers lets you roam for free(EXT coverage) when you're out of their coverage area but dont use the EXT coverage too much or they will cut you off.