Medium Tank: Panther, after all you said the best, not most effective
Heavy Tank: JSII, beats the Tiger hands down with only 1 main problem (lack of ammunition carried in early marks)
Strategic Bomber: B29, though I have a fondness for the good old Lancaster given it's high payload and versatility
Tactical Bomber: No contest, Mosquito wins hands down.
Jet Fighter: Me262, though personally I don't rate the plane that much anyway
Semi-Automatic rifle: Well given the categories you posted I'd put theFJ42 (the paratroop rifle for the Germans) in, nothing can compare to that.
Bolt Action: Lee Enfield, most accurate rifle around
Light Machine Gun: Bren, MG42 I consider more of a medium MG. The Bren could be fired from the hip with some accuracy, the MG42 could not realistically say the same.
SMG: MP40 or MP44 if no assault rifle category
Pistol: Walther
Medium MG: MG42
Amphib: Buffalo, but the DUKW deserves a mention too here
Best Light Tank: Stuart
Best Tankhunter: Jagpanther, anything that marries the killing power of a Tiger II with the speed of a Panther has to be good
Best SPA: Katushya
Hand-Held: Panzershrek
Sub: Type 21
Amphib. Aircraft: Sunderland
Light Transport: Jeep
Heavy Transport: SDKFZ 251 due to it's various different types
Transport Plane: C47
Best Ship: The most used form of US carrier
I disagree with bugfatty300 on the carrier plane as the seafire (IIRC) has a better record than any of the allied planes, and since the criteria is not whom did more, but what was better...
And nonconformist... since when has a matilda been a light tank?
