Most underated albums......

Eagles "On The Border" I think this is their best but i never see it see it mentioned.
Its about the only Eagles album I can listen to beginning to end.

Here's six LPs and two CDs that have given me a great deal of pleasure (and that you may have to hunt for):
Louis Armstrong: Louis With Guest Stars, Jazz Heritage Series Vol. 7, MCA-1306
Johnny Hartman: Once In Every Life, BH 7012
The Tony Rice Unit: Backwaters, Rounder Records 0167
Jazz Critics Choice, Columbia Records, PC 36807
Norman Grantz Jam Session/The Charlie Parker Sides, VE-2-2508
Pharoah Sanders: Rejoice, Theresa Records TR112/113
Claudio Roditi With Paquito D'Rivera, Milestones Candid CD79515
Trio da Paz: Black Orpheus, Koko 1299

Phasecorrect every single one of your list has been critically lauded and are very well known in the alternative world.
They may be obscure to the mainstream/average music fan but they've certainly never been underrated.
Sorry for raining on your parade but Audiogon is creaking at the seams with misread replies and countless suggestions that don't fit the description either in country of origin,timescale or whatever.