I think it relies upon your inclinations and your arranged goals. In any case, you should understand that Canada is HUGE!!
Without giving any contemplations to the size and separations of these destinations from each other, here are my main five. Had visited the first and plan to go to others soon.
Niagara Falls, ON: The lofty falls on the Niagara stream, isolating Ontario, CA, and New York, US.
Haskell Free Library and Opera House, QC: The library that is part between Vermont, US and Quebec, Canada. You can enter through one and leave through another nation (simply ensure you are lawfully permitted to enter the other one generally will prompt quick extradition back to the main nation).
Alert, NU: The northernmost forever occupied spot on Earth, at 82°30'05"N, and just 817 km from the North Pole. In any case, just 5 individuals live there all year!!! Amazingly cold and not all that simple to get to (making it a difficult objective. I long for going there).
Sound of Fundy, NB/NS: The most noteworthy tidal range on the planet with 16m! Be cautioned, you can never surpass a tide with that go.
Banff National Park, AB: What a stunner the Canadian Rockies have! Dazzling!
I think, with the exception of 3, other 4 are very feasible. Here is another possible one I think.
Singing Sands Beach, PE: The shorelines of Prince Edward Island that sings. Checking the video beneath, it is increasingly similar to a squeaking sound I thought. Need to visit to make ends.