SSG vs Para (SF) is an interesting exercise for obvious reasons, I will throw in some comments but with caveat that you cannot really rank 2 units, they are just different just like 2 individuals are different.
SSG's biggest advantage compared to Para SF is that it is not just a regiment, it is also a formation with its own commanders. Everything is integrated including training and procurement. Para SF for example does not even have a regiment of its own though in AFSOD at least there is a higher HQ. On our side NSG and SFF are somewhat similar in that they have a vertical structure.
It is surprising to me still, but Pak Army actually does not have any airborne regiment. SSG is all that they have.
There are rumours that Para SF and SSG went head to head in Kargil though result is not known. SSG's public record is poor, be it 1965, 1971 (genocide), Op Meghdhoot, kunduz airlift, lal masjid etc Whereas Para SF public record is generally considered to be good.
It is 99% chance that SSG would have infiltrated into J&K as jehadis over the last 3 decades. In Afghanistan they must have worked under cover as Taliban. Difficult to assess whether these ops were successful. We keep saying they work as BAT - but again is that successful or not? worth a debate.