let me make it simple for you.
There american,Europian,Russian,chinese planes which you think you can get.
Europian ones are too expensive and they wont give it on soft loans.so Pakistan cannt buy them,even if they buy,they cannt in numbers to make a real differance.
Russian,i dont want to say much if you belive they will sell few planes and risk Indian market,good for you.
Chinese,if the chinese planes are anywhere near good and reliable as the western ones,they would have inducted some chinese planes,the point that PAF have not inducted any chinese high end ones inspite of them getting on soft loans should tell you something.
That leaves American,they wont sell you any other fighter other than F16,that too they have to fund part of the deal.you must have seen many Pakistanies wondering PAF's obsession with F16 which is sanction prone,some come with strange explanations like ,single engine,they know in and out of F16 and what not.but the truth is PAF has no other choice.