SRK is actually a brilliant actor if given the right script and director..The problem is he has just stopped experimenting off late and is caught in the image-trap..You add to it the fact that he has a terrible script sense and prefers to stick to his friends and you have a perfect recipe for disaster right there..On the other hand,Aamir has a brilliant script sense and doesn't shy away from giving another actor the spotlight..For instance, i always felt Siddarth had the better role in RDB and stole the show..Similarly in 3 Idiots, Sharman and Madhavan had really meaty roles..And in Talaash, Bebo stole the show and overshadowed Aamir in quite a few scenes..I highly doubt the fact that SRK or Salman would ever do these movies in the first place..Thats the primary difference between SRK and Aamir..If SRK stops thinking about BO results and choses scripts sensibly, he can still give amazing performances..
P.S.I know many SRK fans loved JTHJ and i do believe Sharukh was really good in the film but i honestly feel the guy is made for better stuff..The script was full of loopholes and the lead pair had zilch chemistry..SRK still has the charm to play a romantic hero provided its a mature lovestory and he is paired with the likes of Kajol, Juhi or Madhuri..