Ich Tote mich... It's like the demo. Very atmospheric and simple but not nearly as dark.
Todeswunsch. This is more medieval/folk but excellent if you give it a chance.
Dead Lovers' Sarabande I & II. These are both melancholic and bleak but very worthwhile.
La Chambre d'Echo. Almost going in a darkwave direction but excellent. It has a very foreboding quality to it. If you like the Es Reiten re-recording you might like this one. Flowers in Formaldehyde is a great companion EP.
Have You Seen This Ghost? A bit too silly lyrically for me but musically very theatrical and dark. It feels like a gothic musical.