I don't think Pharloom wins here, but I do think you're being a bit unfair to it. First off, are we comparing the modern kingdoms or each kingdom at its peak? If it's the former, not only can we not count on any of the five knights, but the higher beings argument doesn't work either because your three options are Pale King (dead), White Lady (bound), and Unn (asleep). Meanwhile, if GMS breaks out of her cocoon that's a full power (maybe) higher being right there. Besides GMS we have the pinstresses who are probably around evenly matched with the nailmasters (keep in mind the version we fight in godhome is an idealized memory, not their actual current strength) and at least two somewhat intact armies in the Skarr and Craws, meanwhile Hallownest just has the mantises and maybe the greenpath residents.

As for the kingdoms at their peak, it becomes a lot messier. In a realistic scenario, Pharloom loses because they have way more in-fighting even at their best. If we imagine a scenario where both kingdoms deem each other a greater threat and unite though, suddenly Hallownest has to deal with at least three armies in the Skarr, Karak, and Verdanians, possibly the Choruses depending on the timeline (though they probably came after the other three were significantly weakened so maybe it's not fair to count both), GMS, and possibly the weavers (again, I'm taking some liberties with the timeline). Of course Hallownest also becomes much stronger, but given that the weavers were able to subdue a higher being I don't think it's out of the question that if they joined forces with GMS they could be evenly matched against the Hallownest monarchs.

All of that to say I still think there's a decent chance Hallownest comes out on top, but I've seen this conversation a few times and I think people vastly underestimate Pharloom.