I think its not correct to compare actors of different generations.
Still Anyways Aamir is one of the biggest superstars one of the most successful good looking and best actors of all time having unmatched script sense and marketing skills.
Aamir has 2 more decades of Acting career left he will achive many more landmarks.
I think even if comparision has to be done we must do a comparision only after that.
I feel except Amitabh bachan and Salman khan none can be compared on terms of commercial success.
And in terms of critical success or acting skills or amount of Respect commanded It will be only with Dilip sahab.
In terms of overseas only srk can be compared.