An interesting discussion.
Mahle, Hengst and Mann are all German based as mentioned above but I know that Hengst and Mann have manufacturing around the globe such as China, Korea and Brazil. Mann set up manufacturing in Korea to cater to all the automotive and marine industry so when I oil/filter change the Hyundai and Kia we have, I fit Mann filters and also to the VWs we have since Mann is VW's OE filter. No reservation in using Hengst or Mahle filters which I have done and can their confirm visual quality but Mann is OE to the cars we have.
Purflux filters seem decent but its sister company Fram seems to have had a lot of bad press over recent years.
All the cars we have use 5w30 so I use VW504.00/507.00 spec oil in them all.