As some know, I rather vote on things that are used in far more theaters, however one theater we have absolutely very little for is the Balkans theater of Operation.
First Aircraft is an Italian workhorse the Fiat G.50

Nothing to fantastic about this aircraft, it carries a pair of Breta 12.7mm machine guns with a top speed of 300mph at 5,000 meters, impressive it was Italy's first all metal Monoplane, and served the Early War in the Balkans and North Africa Campaign.
In addition to this the Italians used the SM-79 as a bomber which we have a few threads on.
Its rival was the British Gloster Gladiator

This is a bit interesting as its a British Biplane fighter used by the RAF and Royal navy. Although it was pretty outclassed by WW2 standards, it actually held its own in combat.
Top Ace for this aircraft was South African Marmaduke Pattle with over 15 victories against the Italian Airforce. Not only did it serve in the Balkans, north Africa but also defended Malta.
There was also a Sea Gladiator version which flew off Carriers.
Although its top speed was only 253 mph at 14,500 ft and armed with 4x 303 machine guns.
In addition to this, the RAF used the Hurricane.
As for the Germans, we already have a 109-E, Stuka and 110C, this would encourage adding the He-111.
Reason I say this, this opens the door to more Early War scenarios in the Mediterranean theater, all planes listed above fought in the Balkans as well as North Africa.
While true none of these aircrafts are going to compete in the Late War arena, they did serve quite well in the opening years of the war.