I think the meta narrative across SRK's career has been quite strong. I think it had a lot to do with his choice of earlier movies. One of the major reasons of SRKs fame in early 90s was his Deewana charactwer, where basically he did much more than normal heroes to get the girl. The same happened with Darr and Anjaam where his character was insanely in love but couldnt get the girl. THis sort of made SRK a sympathetic character and he got a lot of media mileage out of it. This sort of predisposed SRK towards the advantage of a solid meta narrative for movie actors. He must have learnt from a similar narrative of Akshay Kumar about action hero and how AK gained even though Akshay hardly did stunts better than others.
On the other hand, Aamir it seems has avoided the meta narrative thing and has focussed on each movie as a single entity. And thats why i think Shahrukh is a bigger star evewn tho Aamir is the better star.