Whilst we all love to debate the merits of favourite planes, few can be regarded as being designs that changed the way the war was fought in Europe.
for instance whilst the Spitfire and Me109 were capable aircraft neither was a "game changer" that forced rapid development or change of tactics on the enemy.
off the top of my head I can think of four that did:-
It's appearance on the western front put the Luftwaffe in a position of technical superiority over the MkV Spit and drove development of newer and faster Spits, along with more powerfull designs.
as far as I know it was over six months before the MkIX Spit came into service that resored the balance.
In many of the memoirs of fighter pilots I have seen mentions of the overnight change of attitude of the Luftwaffe pilots, I believe it was Al Deere who stated "it was suprising to see the way the FW pilots stayed around and got stuck into the fight when hunched behind the controls of a 190, a marked difference to the one pass and dive away tactics of the 109's, sound tactics when fighting spits in a 109"
This fast light bomber and fighter bomber gave the Allies an ability to take the fight to the enemy and had the speed to survive in hostile skies, a marked contrast to earlier designs.
it's performance led to Goering commenting on allied technical superiority in the air and the forming of a unit dedicated to intercepting these aircraft.
At last the Allies fielded a highly capable aircraft that had the range to escort the bomber all the way to Berlin, we can spend all day debating the relative strengths and weaknesses of differing types but the ability to fly an advanced escort fighter that distance made a considerable change to losses and morale on both sides.
the nail in the piston engined aircrafts coffin, it may have been no dog fighter but that was irrelevant as the bomber is the true instrument of air power and these aircraft were the perfect answer to the bomber, if enough of these could have been produced, pilots trained and fuel produced, the air war could have been tipped on its head as the threat they would have meant to the daylight bombing campaign would no doubt have prolonged the war, probably the biggest game changer of them all.