The Gun law of 1968 stopped importation of German made Walther TPH pistols in 1968 except for a few allowed for sale to LEO's only. The German made ones are considered the best. Interarms imported parts into the USA after 1968. These parts were assembled into stainless steel pistols by Ranger Arms in Alabama. I have owned a couple of the stainless Interarms marked TPH's and both worked flawlessly. Some folks have reported jams and other problems as well as a few small parts breakages like the magazine catch. There is no "best" answer to your question. If you really want one, all you can do is buy one and hope to get a good one. Plenty of spare parts are still available. No new TPH's are manufactured now even by S&W.
HTH
Charlie