I’m based in YYZ.
I have over 500 lifetime rentals from both Hertz and National at YYZ.
My advice is to rent from National when at YYZ.
National YYZ has Polestars or at least did before there was some kind of recall (they were unavailable for a bit).
I have been upgraded to Polestar from my corp rate full-size rate more times than I can count.
National YYZ staff are generally helpful. Hertz YYZ staff are overwhelmingly useless.