Simrock (15th ed., 1884).
Modern German versions are by Simrock (very close to the original) and Hertz (freer, but with excellent notes and appendices); Eng.
Gottfried's Tristan and Isolde has been several times published; the best editions are those of Bechstein (1890) and Golther (1889); modern German versions by Kurz, Simrock and Hertz; English prose rendering, J.
Von Schlegel, the diplomatist Christian Karl von Bunsen, Robert Schumann, Karl Simrock, E.
There are modern German translations by Simrock (very close to the original) and Hertz (excellent notes).