It's very difficult to recommend a whole album on a singular artist under these genres. I always tend to find good songs with various artists on compilations. I've always been a fan of Portishead, and I've always been on the hunt for more music like them. Now, I have so many to recommend, but I'll start with these albums:
Kallocain by Paatos check out Holding on, Gasoline, and Reality. The album was mixed by Porcupine Tree's Steven Wilson. It's a mixture of downtempo/chillout/Prog-Rock.
In the same vein of Portishead, my highest recommendation will go to:
Mandalay check out their three albums, and then after Nicola Hitchcock's latest solo album:Passive Agressive. Her voice is very unique and angelical.
All India Radio - Fall - Hypnotic Voice and rhythms!!!
More along the lines of Tricky/with more Hip Hop and Jazzy elements, I would have to say, try:
The Herbalizer anything by them.
Wax Tailor- Tales of the Forgotten Melodies, and their latest Hope & Sorrow album.
For the Best Compilations you should try:
Hed Kandi - Winter Chill albums. Huge variety of female artists.
Trip Hop Anthology
Very rare stuff:
Brother sun, sister moon- Great Game
Both albums produced by Paul Robb from Information Society. Barbara Cohen has a very soulful voice combined with the cool Trip Hop tracks by P. Robb.
I have lots more, but this will suffice for now.