There was an airshow here in town the this weekend and an original Bf-109 with original engine flew in for it. I unfortunatly only saw it on the news as I was flying.
When I was working at Mojave airport and they were flying "white 14" you could always tell when it was in the air. Spits, Mustangs, P-47s, a Bearcat, a Zero, and Corsairs have flown in from time to time, after a while you know the sounds of those engines. When the 109 flew over it had a low rumble unlike the Merlin or Allison.........
A number of years ago I was at Duxford mid week when they flew two original 109's. It wasn't a flying day, they just did it beacuse they could and wouldn't have the oppertunity again. One was Black6 and the other was one they had just finished working on. It was a special sound.
I have a picture somewhere if I can dig it out, but its an old one.
My list is reasonable based off A) Ability B) Combat record C) Impact.
The B-29 wins hands down on ability, it's combat record wasn't massive but it had a huge impact. The Lancaster is second in ability, and a great combat record and impact on the war in Europe (but not in Pacific). The B-24 dropped more tonnage than any other bomber of the war, it was third in overall ability and a great impact on all theatres. B-17 was good, had impact in both ETO and PTO but was not MASSIVE and had an impressive combat record. The Halifax was a decent bomber, with decent combat record and not a massive impact.