The ONLY one I would spend money on would be a PTR-91; they are made here on tooling purchased from FMP, which was an HK-licensed manufacturer in Portugal. All the others you mention are built on parts kits and receivers of dubious quality, and should be avoided, IMO.
An option that splits the difference between the PTR-91 and a real HK-91 would be an older Springfield SAR-3 or SAR-8. These were manufactured in Greece by Hellenic Arms (again, an HK licensed producer) and imported by Springfield. Later SAR-8s were built on US-manufactured cast receivers with a rail on top and should be avoided.