Hasek and Dryden are each a product of their times, just like today's goalies. Send a goalie from today back in time and nobody would score, that's how vast the evolution has been at the position. It's circular tho, you can say give the old players fancy sticks and skates, etc. So you can't just compare apples with apples between these two.
Hasek wasn't just acrobatic, athletic, but his was a style evolution in the sense that he worked with Corsi and his dmen to push shooters to seemingly attractive spots, which were really medium danger and fully in his wheelhouse. So, yes he played on a weak team in a loaded salary era, but they had an edge on other teams in their systems play which allowed them to level the playing field.
Dryden was also an evolution because shooters had never seen anyone that big be so quick on his feet. He was probably best on the ground, even tho he played mostly a standup style. Also, the 70s were a watered down expansion era and the Canadiens were a stacked team.
Today's goalies are another leap even from Hasek. They have to face 23 guys who can all shoot the puck with no release and get called garbage even if their defense gives up a barrage of high danger shots (we're currently in a high offense era). Most of these goalies today are stellar commpared to the proto guys.
In 20 years the position will evolve again and they'll come up with another way to cover the net or a system that will push shooters away from the high danger areas. Or the dmen will get bigger again and be even more athletic. Something new will happen, and those goalies will surpass Price, Shesterkin and whoever you currently have at the top of your list.
So, yes Hasek was better, but it's relative to era. That's how I see it.