P-51 Mustang

The P-51 Mustang was perhaps, no definitely the best propeller driven fighter ever made. 

This is the fighter that wiped out the German Luftwaffe in the later years of the war in Europe. It was fast (still is) heavily armed and armored. The P-51 saw action in every theater of WWII and was feared and successful. 

The picture above is of a P-51 taking off from the island of Iwo Jima. They were based there to fly cover for the B-29 bombers that pummeled Japan. The U.S. Marines lost more men taking Iwo than in any battle in WWII. Iwo was the only battle in WWII where the Marines had more casualties than the Japanese. 26000 Marines were wounded in 36 days, 6800 were killed. The Japanese had 22000 men on the island and all but 300 were killed. The U.S. army air corps estimated taking Iwo saved the lives of more than 20000 army air pilots and crewmen. The air assault on Japan could not have happened without the Marines securing the islands 3 air fields. The Japanese could have shot down most of the B-29 bombers as they passed Iwo on flights from Tinian in the Marianas en-route to Japan where Japanese homeland fighters could pick off the rest. Iwo gave a support base for P-51 aircraft to escort the B-29 bombers into Japan and a landing field for returning bombers that were damaged to land on American airfields, saving planes and crews that could not make it back to the Marianas. 

After WWII the P-51 was sold to countries around the world and saw use in air forces in nearly every industrialized country in the world. The P-51 was I think the best ever made. Converted models still fly in air races around America and they do well.