imo...

german = too complex, tempermental by design.
Japanese = complex, perform well but cost is high.
American = does america actually build a pure american built truck anymore?
Assembled in america does not mean what it used to anymore. Made in America just means it was assembled here. Well yes i am being harsh because there are some mfg's that still do build their trucks in america but also do the same in other countries as well in a global setting for convenience.
But i can't say american units are any better or worse than any other...
All forklifts these days have become so complex and bloated with electronic fluff it's rediculous and has driven up costs dramatically and require specialized training to even service most of them. Of course specialized training has always been a thing but these days you can't do much without a handset or laptop anymore.
But with all that said, if i had to pick between the 3, i'd lean towards japanese built trucks, they are built better and give less trouble.