Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
I'd place the Finns at #1 not only because they were completely outnumbered, but because unlike the Italians who were manufacturing first-rate aircraft, the Finns were pitting obsolete and outclassed aircraft against more advanced fighters and making the enemy pay dearly for thier airspace.
Actually, the Italians had a decent sized airforce compared to Romania, Hungary, Bulgaria, etc.That much is true, but you also have to consider the RA was fighting on multiple fronts with the smallest air force of the Axis powers, and was working with a fraction of even their previous small size after 1943.
And I don't know about "first rate" aircraft, they had some great if underarmed (until Serie 5) fighters from Macchi, Fiat and Reggiane and the SM.79 was a decent medium bomber but their other aircraft were decidedly lacking in reliability and/or performance, or weren't produced in significant numbers. Their pilots still did a good job with what they had available.
Actually, the Italians had a decent sized airforce compared to Romania, Hungary, Bulgaria, etc.
As far as the Italian's aircraft, they had some exceptional machines!
Just imagine if the Finns had aircraft like the Macchi MC.202/MC.205 or the Fiat G.55!!
What about the Polish AF? Polish pilots in PZL-11 fighters shot down over 170 Germans. Plus look at there contribution in the exiled Polish Air Force in the UK, though they were not using Polish planes, the still had a large impact.
Finns are not underrated, I think everyone acknowledes that they were very good. I agree with Coberkane, the RNZAF. Held the fort in dark times for the RAF in the far east. But you don't hear much about that.
On my patriotic side: the Dutch also shot down quite a lot of ac with only 120 aircraft of which most were horribly obsolete. The LW lost over 400 aircraft ot of aprox. 1200 here in 5 days, but I must admit, the majority to AAA. Stil I think they deserve an honourably mention.
The American Air Forces (land and naval) was 'under rated' at the beginning of WWII. The Japanese, Germans and Brits all rated the USAAF and USN aircraft as 'below par'. The pilot pool was marginal when compared to the three when Our war started.
To suggest, as the opening thread statement suggested, that the primary attribute of the US was "that the USAAF and USN's level of supplies and equipment were virtually second to none' is pretty humorous. Somewhere in between December 7, 1941 and September 2, 1945 there was more to US Airpower than 'supplies and equipment'.