As I said at the end of the Kalkhoff review, to some extent this depends on what one's view on e-bikes is.
If it's to be still a bicycle with some electric assistance added without spoiling the bicycle side, then it could only be a bike with a Panasonic unit, and regardless of cost as you've specified, that would be the high end BikeTech model, probably around £2500 at present, though I understand there's been some reductions recently since the Kalkhoff launch. Therefore it's a European bike with a Japanese motor unit.
I couldn't really suggest a candidate for the other type of e-bike, generally hub motored, where the power is a much bigger factor at the cost of some of the cycling qualities. The motor part would have to be Oriental, but the bicycle part if Oriental would have to be from an experienced cycle manufacturer like Giant to qualify.
The Swizzbee is out of the frame for me for several reasons, it's in the second group but has a dated motor which is a flaw on such a bike, and has to be pedalled off the mark, a characteristic which doesn't sit well in that group. The whole thing is a bit "Heath Robinson" too.
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