I consistently find the Korg ARP 2600 FS and M to sound superior to the Behringer 2600. And to my ears, the Korg ARP 2600 also sounds superior to the Korg ARP Odyssey. I know it's only YouTube quality, but there still an amount of sound judgment one can make from careful listening, especially when the results are consistent.
The B2600 utilizes active mixing instead of passive, which I think plays a MAJOR part in the sound. I recall some guy mod'ing both the Boog and the B2600 in this regard, and comparing the sound with unmodded, with quite striking difference. The passive mixer has these weird "spots" here and there when increasing amp for the oscillators, due to some interaction between them it seems. It sounds weird, but in a good way.
I don't know about the Bodyssey, haven't owned one, but the demos I've heard sound so much better than the B2600 for some reason. Perhaps it is "true'er" in design, with passive mixing. I have no idea, it just sounds so much "fatter" to my ears.