PPRuNe is the only such website I use. I did look at Av Canada, but was not impressed, and did not appreciate the whining I read. Though there is bunk here too, even the whiners seem to generally conduct themselves at a higher level.
That said, the Canada forum here does not offer a great deal to me, several other forums are much more useful on a day to day basis.
When you find a good PPRuNer, they're great!