SAR cabs
Cokecan,
I think I'm right in saying that the MK3 and later 3A were designed from scratch as SAR variants of the S61 type. The MK5 was originally an ASW airframe that was "de-modded" by removal of the LAPADS, Sonar winch, spare seats, weapons points, kitchen sink; and had strengthened floor fitted. (Yes I know there is more to it than that, just keeping it simple!)
As to which is best, well as a mechanic I will defer to the aircrew for that answer, but from reading the "Rotorheads" forum I would say both are better than the POS that the S92 appears to be. (Not worked on it but read the threads and see what I mean).
Cheers now