Well that's what I'm trying to say - saying the Me 262 was a more effective aircraft because it was more useful doesn't make sense. The Ar 234 was a bomber, the '262 a fighter - you can't say that the 262 was more 'effective' just because Germany happened to need fighters more than bombers, you can
only say it was more 'useful'. In the same way you can't say that the Condor was more 'effective' than the single-engined types just because it was a patrol aircraft in the Atlantic, but it was definitely more 'useful' in that role.
Oh, and as I've said, I think the '234 was the 'best jet' because (in my opinion) it was more capable of performing its job well than the '262. It's a very close run thing and I must admit that the only thing that really decides it for me relates to the engines. The Jumo 004s, when treated like a fighter engine (i.e. run at high power for extended periods, frequently having their throttle settings changed) had a very short running life (about 10hrs) that drastically reduced the effectiveness of the Messerschmitt Me 262 as a fighter. In the Arado the 004s were handled very carefully and gently by default - it was, after all, a bomber/ recce plane. This lead to increased servicability, longer engine llifespans, and therefore a more effective bomber than the '262 was a fighter.
Never mind, I'm just being pedantic. I get most of my details from Alfred Price's 'The Last Year Of The Luftwaffe', but I will try and get hold of a copy of that book Erich, thanks.