Suggest one obsure album we all should hear

Knopfler -  Good On You Son

Mainstream, but awesome. 
Great textures and groove throughout song and actually the whole album. 

https://youtu.be/JIBCHh-fMUE

Donovan - A gift from a flower to a garden. One side electric and the other side acoustic. The acoustic side beautifully ethereal.

Tom Robinson Band,  "Power in the Darkness"   1960's Brit Rock that still sounds good.

Olu Dara,  "In the World" a surprise pick by Stereophile  Magazine as the album of the month some twenty years ago.

While obscure is highly subjective, I love this post!  So I will post more than one suggestion!

My top two "out there" pics are in the new age-ish category (though new age does these recordings a disservice):

1. Deux Filles - Silence & Wisdom
2. Popol Vuh - Aguirre

If you are into the ECM jazz label, which could be obscure for some but hardly so for others, there is one release that is an absolute gem without much attention:

1. David Darling - Cello

I always loved these two 80s releases which never got too much attention (though some may disagree) ... these are in the 4AD / Dead Can Dance genre:

1. This Mortal Coil - Sixteen Days/Gathering Dust EP
2. Colourbox - Best of Colourbox 82/87

For a last song recommendation, something from a well know band:

1. The Clash - Bankrobber/Robber Dub from Black Market Clash

Michael Chapman - Life on the Ceiling and since nobody sticks to one album, Mother Goose - Stuffed