This is a tough question because you need to take into account the time period and role for the aircraft. Early on in the war in the Pacific, the A6M2 Zero was the dominant fighter and was clearly better than anything it faced. It’s achilles heel was speed though. It lost manueverablility very quickly over 200 mph, so it’s superb dog fighting ability could be negated with boom and zoom tactics from Allied fighters, which soon surpassed the Zero in quality.
Another factor is pilot quality. The Japanese Navy probably had the best cadre or pilots in the world in 1941, but the squandered them away and never developed a good wartime training program. The UK and US put into place the best training programs in the world and by 1943, the average quality of their pilots were vastly superior to the average from any nation they faced. By 1944, an American fighter pilot in a P-40 had a good chance of beating almost any Japanese fighter pilot he faced because he had much more throrough training and the quality of Japanese pilots had deteriorated significantly.
Modelers probably go more for fame of an aircraft than its abilities. The Me-262 is a very popular subject. It did cause a lot of fear in Allied airmen when it appeared, but it was a very touchy aircraft with 1st generation jet engines which was not reliable and had a very short lifespan. It also required a highly trained pilot to fly it, which limited the deployment. There were few Me-262 bases, which were quickly identified by the Allies and there were always swarms of Allied fighters lurking around these bases, which made landing and take off a very risky thing.
Some aircraft are also popular due to some specific event or a reputation held by airmen which may not have been true. The B-17 was very popular with the 8th Air Force and has gone down in history as a great bomber. It had shorter range and a smaller bomb load than the B-24. In operations in Europe, the impression was that the B-17 was a tougher airplane than the B-24, but actual records of how many of each aircraft type were lost vs. number of sorties is about the same. B-24s did make up the bulk of heavies flying out of Italy and because of their range, they often made deeper penetration missions than the B-17s.
Because the B-24 had better characteristics, and was a newer design, the government ordered more of them. The B-24 was the most built US combat aircraft of the war.
Having climbed around in both aircraft and had a chance to ride in a B-24 once, the B-17 gives me more of an impression of solidity. My father flew in both during the war (as well as quite a few other aircraft) and he said he had the most confidence in the B-17.
All that said, my attempt at a list with roles:
US:
Best fighter - Europe
Escort - P-51
Ground attack - P-47
Best fighter - Pacific
Carrier - F6F
Land based - F4U (as pure fighter) + P-38 (range and fire power)
The P-38 was a failure in Europe largely because the turbos were very touchy in cold and damp conditions. The P-61 was the only purpose built night fighter the Allies had and it served this role quite well.
Best bomber - Europe:
Heavy - B-17 and B-24
Medium - B-26, late war A-26
Best bomber - Pacific:
Heavy - B-24, late war B-29
Medium - B-25 (the B-25 had much better poor field performance than the B-26 which is why most B-25s were sent to the Pacific and all B-26s except for some early ones were sent to Europe)
Carrier - SBD early war, TBF/TBM mid-war, SB2C Helldiver late war (the Helldiver had a terrible reputation because of all its teething problems, but was vastly improved by the end of the war and surpassed the TBF in performance)
Anti shipping (land based) - B-25
UK (the British used a lot of American aircraft, some of which were much better than indigineous designs, but I will concentrate on UK designs)
Fighter - Spitfire early war (though the Hurricane did far better in the Battle of Britain than most people give it credit), late war is harder to say since the USAAF was dominating and the Spitfire had too short a range to get into the biggest air battles.
Ground attack - Typhoon, though the Hurricane did well in this role too.
Heavy bomber - Lancaster
Anti shipping - Mosquito and Beaufighters tag teamed in this role and both were good at it.
Night fighter - Early Beaufighter, late Mosquito
Special purpose bomber - Mosquito
USSR (the Russians used a huge number of US and UK aircraft, the fact that they thought the P-39 was a great fighter says something about their indiginous fighter designs. Some of their aircraft were worth a mention though)
Fighter - MiG-3 was a high altitude fighter that gave the Germans fits at higher altitudes, though they suffered at lower altitudes where most of the fighting was.
Ground attack - IL-2 Sturmovik was the only purpose built ground attack plane the Allies had. The Russians built thousands of them. The actual totals built are unknown, but they were almost certainly built in enough numbers to rank as the #1 built combat aircraft of WW II. They were very heavily armored, which made them a tough target to shoot down. Even at that, the Russian production lines had trouble making enough to make up for losses in 1943 and early 1944.
Japan
Carrier fighter - A6M Zero.
Land based fighter - A6M Zero early war, late war had many good designs which didn’t live up to their potential because the pool of pilots had deteriorated too much. Among the late war fighters worth note are the George, Raiden, and Frank. In the middle years of the war, probably the best Army fighter was the Ki-61/Ki-100 Tony.
Cairrier based bomber - Early - Kate, later - Jill.
Land based bomber - Betty
Long range recon - Emily flying boat
Floatplane fighter - George
Italy - Italian industry was not prepared for war. Their engines produced less power than most other nations and they lagged behind most of the rest of the world in airframe design. The Sm.79, though an ungainly looking beast with three engines did perform well as a torpedo bomber against British convoys in the Med. Italian aircraft are becoming more popular as a modeling subject because they have interesting paint jobs.
Germany
Fighter - Early Me-109, mid war - Fw-190, late war is debatable, in piston engine aircraft the Fw-190D and Ta-152 were the best. Though they might have been bested by some of the designs that were in development at the end. The Me-262 is the ultimate boom and zoom fighter of the war, but it suffered from a lot of bugs that were never worked out.
Night fighter - He-219 was the best to see operation, though politics kept the number to see combat small. The Ju-88 and Me-110 did most of the night fighting work.
Medium bomber - Ju-88
Heavy bomber - Germany never put much resources into heavy bombers. Virtually all were used for long range anti shipping in the Atlantic. Early in the war, the Fw-200 was probably the best they had, though it being an airliner by design, the stresses of war duty caused a lot of airframe failures. The He-177 was the only purpose built heavy to see regular production, but engine fires and a lack of a fire wall on the engines resulted in a lot of losses due to operational accidents.
Ground attack - Early - Ju-87 Stuka, later is open to a lot of debate. The most used ground attack plane in the latter years of the war were Fw-190s. The Hs-129 deserves special mention as the only purpose designed tank killer prior to the A-10. Though is was not built in large numbers and did not capture a lot of headlines with its service.
Germany is also notable for a lot of what people have labled “Luft 46” aircraft. There were quite a few aircraft types on limited production, in the prototype stage, or on the drawing boards at the end of the war. The He-162 was not the easy to fly Volksjagder that Hitler wanted, but it was a pretty decent airplane. The Do-335 would have been the ultimate piston engined fighter bomber. The Ar-234 was the first jet bomber and though mostly used for recon, was a good airplane, when they didn’t have engine problems. The Russians plagerized some of the x plane designs on the drawing boards. The first generation Russian fighters were essentially German designs.
As far as weirdest and worst, that’s an entirely different topic. I do have a book on some of the weirdest and unusual aircraft designs. Few ever made it past the prototype stage. If that.
Bill