This sort of thing is all the rage at the moment on the forums and is sorely lacking here.
Here is my top 10, following the one album per band rule. If a band straddles the doom or black genres I've gone with an album that (sort of) fits the gothic metal genre. @Vampyrique I've updated and filled out my list.
10a. Sirenia - 'Perils of the Deep Blue' (2013)
Morten Veland's project has now really become his main event, with many more Sirenia albums now in existence compared with his Tristania work. This album is arguably my favourite of the Sirenia material. It has an epic scale but it's catchy and engaging all the way through, with a phat yet luscious production. This is the second last yet best album he would record with Ailyn on vocals. She has such a special voice.
10b. To/Die/For - 'Jaded' (2003)
This is from the rock side of the genre. To/Die/For were untouchable for catchy melodic music around this era, and this album is just brilliant. Jape's deep voice was in its prime and the songs here are all gothic rock anthems.
9. Saturnus - 'Martyre' (1999)
The final release from the Kim Larsen lineup of Saturnus, this album begins with the beautiful choir of '7' before launching into one of gothic metal's most exquisite moments with that riff from 'Inflame Thy Heart'. This album is just full of near perfect riffs and near perfect vocals with the spoken word, mid range bark and full deep growl. Spinetingling.
8. Moonspell - 'Irreligious' (1996)
We are now officially in masterpiece territory. This is one of many classics from the 90s as you can see from the list. Tracks like 'Opium' and 'Full Moon Madness' are timeless.
7. Tristania - 'Widow's Weeds' (1998)
A true gothic album, this contains choirs, creaking church doors, organs and some incredible metal. Morten Veland's second appearance on the list. That guy is a genius. I went with this, their debut, over the more upbeat 'Beyond the Veil' because this has the real ivy-on-manor-house-walls feel that perfectly sums up the genre.
6. Theatre of Tragedy - 'Aegis' (1998)
I was so tempted to put 'Velvet Darkness They Fear' in this spot rather than 'Aegis', but I think 'Aegis' just wins out due to some nice memories of a girl from university who used to like listening to this when we were being intimate. The band dropped the growls and replaced them with Raymond's dulcet speaking voice, and they amped up the repetitive catchiness and sweetness. What they ended up with was a beautiful album and me getting laid.
5. My Dying Bride - 'Like Gods of the Sun' (1996)
This album really changed my life. Technically I would class 'The Angel and the Dark River' as gothic metal as well, and on a good day I prefer that album, but this album just fits the vibe of gothic metal so perfectly. When I first heard the title track on Australian radio back in 96 I knew I'd found the next level. This is dark with fabulous twin guitar harmonies and a great violin sound back when it was still original. Oh man I love this album.
4. Paradise Lost - 'Draconian Times' (1995)
Paradise Lost are responsible for so much in this genre. This album is nearly perfect in its production, artwork, texture and sophistication. When I discovered this album back in about early 1996 I thought this band was the classiest metal band I'd ever come across.
3. Cradle of Filth - 'Dusk and Her Embrace' (1996)
Writing out these little reviews is bringing home how important this genre is to me. Cradle's 'Dusk' album is a theatrical masterpiece. Romantic keyboards, epic soundscapes, beautiful gothic riffs and some of Dani's best lyrics. Amazing artwork too.
2. Anathema - 'Alternative 4' (1998)
Is this gothic metal? It's close enough and I'm running with it. The violin, piano and mournful guitar riffs all work on crushing the heart with some of Vincent's best vocal lines and Duncan Patterson's best lyrics. Yes, 'Fragile Dreams' and 'Inner Silence' are well recognised classics, but check out 'Lost Control' and 'Feel' for crying out loud. Just amazing. I used to have 'Feel' on a tape that I had recorded from the radio back in 1998. God, what an era.
1. Type O Negative - 'October Rust' (1996)
And here's number 1. This isn't just my favourite gothic metal album of all time (which is bloody saying something, let me tell you), but it's also probably my favourite album of all time of any genre (if that's even possible to call). Peter Steele and Josh Silver are just so far beyond the rest of the planet on this album that it's hard to believe it was created by humans. Songs like 'Love you to Death', 'Red Water (Christmas Mourning', 'Wolf Moon' and 'Haunted' are untouchable. 'Be My Druidess' has one of the greatest ending riff/vocal lines of all time. Everything about this album is romantic, emotional and gothic.