I referred to
this thread when I did mine.
If I recall (somebody correct me here)
Corteco is OEM for the original seals.
Whether the current Corteco seals are significantly superior I could not verify, and for the sake of confidence in the updated design, I went with the Elring set. Gold outer, red inners, I did not think twice.
The factory inners were hard as bricks on half of mine, and the others were close to it.