It's a comlicated comparison. Let's look at the history of IRAF.
During Shah's time, IRAF could have gone toe to toe with any Air Force in the world. They had the best equipment, they had the best pilots and they had a strong economy and population to back it.
Come Iran revolution, a lot of experienced Air Force pilots either go into exile, or are purged and killed due to fears of a military coup. A good pilot in an average plane will always beat an average pilot in a good plane, at least that's what most air force experts seem to think. I believe the purge was stupid and ruined the professional military's capabilities. That said, I do think Iran revolution was the right way for the Irani people. Putting up with a tyrant just because he was cozy with the west is not a smart choice.
Now what about the current capabilities? Most people think that IRAF has become weakened after the Iran revolution. Meaning if IRAF of 70's went against IRAF of today, the 70's IRAF will win. I think that is naive and arrogant. Western equipment is not some supernatural technology that no one can replace or replicate. First you need to ask, what the hell is so advanced about those 70's planes today? Mind you, 40 years have passed. Do you know what 40 years means in today's world? It is very condescending to think that Iran will not have surpassed the 70's technology even after 40 years.
As for combat experience, they most certainly do have combat experience, and a significant amount of it from the 1980's conflict with Iraq. And I think they performed on par with Iraqi Air Force, as neither achieved complete air superiority over the other through out the conflict.
That aside, i do think that the
RATE of technological improvement has most certainly slowed considerably due to the sanctions and lack of military technology transfer. If 70's IRAF was given a score of 100, Modern IRAF will have a score of 130, whereas without the sanctions, it would have had a score of 220 or in the whereabouts.
With that insight, let's go into the comparison.
Firstly, what do you mean by PAF vs IRAF? Do you mean a total war? Do you mean simply destroying each others planes? Do you mean destroying each others planes, airbases and radars stations to achieve air superiority over the opponent? I think I will go with the latter, as that makes the most sense.
Let's look at the numbers first, we will use
Global Firepower - 2015 World Military Strength Rankings as reference.
--------------------------PAF--------------------------------IRAF
Total aircraft------- 914----------------------------------471
Fighters---------------387---------------------------------119
Trainers---------------170---------------------------------78
Transport------------278----------------------------------196
Serviceable---------151----------------------------------319
AIrports
Helicopters----------313----------------------------------123
Atk Helicopters-----48-----------------------------------12
Numbers wise, PAF does have an advantage. PAF has three times the numbers of fighters as IRAF. But numbers aren't everything.
Technologically, PAF has several AWACS, Block 52 F-16's, the latest AMRAAMs, and the crown jewel Ra'ad, Which is an Air-Launched Cruise missile with a range of 350 kms, perfect against Stand-off strikes on Radar stations.
Iran too has improved on it's capabilities. It has reverse engineered the Phoenix missiles and the HAWK SAMs. But Phoenix BVR missiles were originally made to be used against slow moving Soviet Nuclear bombers, it's capabilities against maneuverable fighters is questionable whereas AMRAAMS are deadly at BVR.
As for AWACs, Iran does not have any AWACs planes, but during the Iran-Iraq war it did use its F-14's as mini-AWACs. Meaning they were used to detect incoming enemy aircraft from long range and then directing other aircraft towards them. So they do have some AWACs capability.
They don't have any long range Stand Off weapons for their air force. They do have some land based very long range cruise missiles but the OP asked us to exclude surface to surface missiles.
PAF has in its inventory several laser guided munitions for accurate airstrikes, IRAF has no such capability that i know of. PAF can carry out night time strikes, but that capability is limited to F-16 Block 52's for now so its very limited. Iran has no such capability.
Now lets discuss training. As you can see the numbers, Pakistan has a much larger number of trainers than Iran. That means PAF can train more crew, in a shorter period of time compared to Iran. Pakistan also manufactures it's own trainers, so that is another advantage.
That said, it doesn't change the quality of training. And quality comes with experience. PAF trains regularly with China, KSA, UK, USA and Turkey. It also takes part in European exercises from time to time. So it is safe to assume PAF knows modern combat tactics head to tail. As for IRAF, although they don't take part in multi-national exercises like Pakistan, they do carry out very large exercises within their country. Both improve training of the pilots, but i am inclined to believe practising against different aircraft from different air forces is more beneficial.
The biggest advantage that Iran has over Pakistan is that Iran is much larger geographically. That means, PAF will have to travel longer distances to strike Air Bases. That also means Pakistani air bases will be very exposed. They will have very little time to react when IRAF carries out an airstrike.
To negate this PAF does have air-to-air refueling. That means Pakistan will be able to have aircraft airborne for longer periods of time. That will help immensely and is a force multiplier when it comes to defending your Air bases. But you cannot carry out air-to-air refueling over enemy territory. Not unless you have complete control of enemy skies. So PAF will have a lot of trouble reach western bases in Iran.
But tables can be turned the other way round. Being larger means Iran has a much larger area to defend. Does Iran have sufficient SAMs to defend each and every air base? PAF is very likely to find holes in their defence through which it can poke. Pakistan is smaller so that means Pakistan has a smaller airspace to protect, fewer SAMs needed. And with a larger number of aircraft, Pakistan will have an extremely concentrated Airspace, It will be very hard to operate in for IRAF.
Another disadvantage of Iran's geography is mountains. Yes, Iran is more mountainous than Pakistan, especially the border regions. What this means is that PAF will be able to fly in the cover of those mountains and remain undetected by radar. To counter that you need to build Radars at the great heights. Still then, careful planners will be able to find holes in their coverage. The best counter to mountainous areas is to operate AWACS, as they negate the weakness of radar coverage, but Iran is limited in that area. Most of Pakistan's airbases are located in plains. Although the Balochistan area is very mountainous, PAF's AWACs will prove crucial there.
Another problem with Radars is that you have to defend them. PAF has a larger number of stand-off weapons. A single Ra'ad fired from 350km away can do significant damage to a radar station if not completely destroy it. PAF also manufactions its own Glide bombs, which have ranges from 60km to 120km, that is another havoc for IRAF.
Iran also has a larger number of airbases/airports. That means PAF has many more targets whereas IRAF has fewer targets to destroy. So that is also a big advantage.
Considering all this information that i have gathered and pondered upon, I think PAF enjoys a significant and decisive advantage over IRAF. IRAF will be able to operate aircraft from its western bases for a very long period of time, but as it loses control of skies over eastern areas, you can expect PAF to carry out more and more daring airstrikes with the use of Aerial Refueling and Stand Off weapons.
