As far as Das Boot is concerned, my vote is for the original TV mini series (but I'm probably biased since that is the first one that I saw). The original theatrical release was a collection of all the action scenes which changed the pacing substantially, and also altered the character of the whole story. The original story is all about the endless boredom that is war, interspersed with terror, and then a few absurd moments and hard partying either in anticipation of another tour, or in celebration of still being alive.
Obviously, for a cinema release you can't have all the boredom in it, I understand why those decisions were made. But still, the TV series towers above the cinema versions. The Director's cut is, of course, still better than the wretched US theatrical release version.