Pakistan Airforce must be considered in the top ten airforces of the world on the basis of its past performance and training procedures.
Way back in 1999, i was posted in the FT-5 detatchment of the training wing as a student. As the Kargil war broke out, our detatchment started to train on war footing. We had DACT with our opponents being the F-6, F-7, Mirage 3 and even F-16s. We were trained for a low level air-to-air combat and believe me that while flying in a Mig-17U [FT-5] we outfought the F-6s and Mirages, and even won twice against the F-7MPs. This shows our low level of training since FT-5 was the first jet fighter we ever flew. You can think about our senior pilots who had quite a lot of flying hours on the most modern fighters. Espacially the pilots of the F-16, F-7 and Mirage units had the experience since they had flown against the Mig-29s, F-15s, F-16s, Mirage 2000s and Mig-23s of the friendly countries in DACT.
When PAF was tested in 1965, its proved its mettle by stopping and inflicting serious damage to the more modern, advanced and large IAF, while it remained unscathed loosing only 16 aircraft in all.
Again in 1971 PAF saved Pakistan from humiliation when again it flew for the defence for its country. At this time the total amount of PAF aircraft numbered less than the total no. of front line IAF aircraft but still it performed well. It stopped the indian advance in East Pakistan till the last moment when it was in a no win situation, since the IAF outnumbered PAF both in quality and quantity. Even in the western sector PAF flew important strikes which kept the indians at bay, otherwise the western sector would also have faced a certain defeat. Though Pakistan lost this war, PAF had lost 34 aircraft but it also downed 102 IAF aircraft. The result of the PAF failure was not that they were inferior but it was due to internal situations i.e. the bengali factor and the main commander, Gen. Yahya Khan was incapable of fighting this war. The PAF had fought on its own during this war with only one objective; conserve, survive and defend. This it did properly.
Then during the Afghan war, PAF again saw action against the Russians and shot down half a dozen of Russian/ Afghan intruders without loosing any aircraft to the enemy.
PAF pilots have flown as instructors in the Arab countries and have performed extremely well against the Israel airforce. PAF pilots while flying Hunters and Mig-21s have downed a few Mirages and Super Mysteres without loosing a single PAF pilot or aircraft flown by PAF pilots.
Though PAF is not that much advanced as its enemies, it knows how to deal with them in their language and as far as it is training is concerned, its been rated as the best. According to my opinion PAF should be rated among the top ten airforces in the world.