We can say that last KW version and last Zfac version are on par, with some differences. The choice will be just a taste matter
KW evident flaw: the upper external edge of the bezel narrower than gen and no well polished
ZFac evident flaw: The cannon pinion ZF type with raised ring. The upper external edge of the bezel is not accurate but better than KW
Movement:
KW can be fitted with KW P.3000 decorated Seagull NON-inverted KP9000-Seagull V2, with balance wheel @6 whereas gen is @7. Accurate enough and reliable.
ZFac last version is fitted with the ZFac P.3000 decorated A7750 NON-inverted and improved decoration ZP9000-V2.5, balance wheel is @11 instead of @7 like gen, but the overall layout is quite accurate when the movement is rotated about 90º.
Regarding price: the best price would be KW with Seagulll NON-inverted
Material:
We know the composition of KW: Bronze almost the same as gen:
Read:
KW PAM382 Bronze material – Official Chemical Analysis (the definitive answer) ******
http://forum.replica-watch.info/vb/...mical-Analysis-(the-definitive-answer)-******
We have no info about ZFac material
Lume: KW versions had better lume than ZFac, but I don't know about the last ZFac version
Up to you. Make your own decision
ALE