Akshay is far better in terms of action e.g. Khiladiyon Ka Khiladi, Mohra, Main Khiladi Tu Anari, Waqt Humara Hai, Awara Pagaal Deewana and ect.
I'm a fan of both actors but Akshay is much better because he's done a very good job adapting to diffrent roles and genres e.g Sangharsh, Ajnabee, Jaanwar, Baby, Special 26, Aankhen, Khakee, Patiala House and ect. Once Upon a Time a Mumbaai 2 was a bad movie but at least he had the guts to play Don which was a very challenging role. That's the thing with Akki because he's always commited to facing new challanges e.g roles & genres which is what I like about him. I would like see him do a political movie like Ranjneeti or Sarkar because I'm pretty sure that he would do an excellent job if given a good role.
Salman is a good actor and no doubt his stardom was bigger than Akshay's in the 90s and and it currently is right now. Like I said Akki excells on the acting side e.g. Action, Comedy and even negative roles.