Grateful Dead - Workingman's Dead (Warner, 50th anniversary remaster, first released 1970)
Back to my comprehensive listening/cataloging "project", recharged by an upgraded amp that has me hearing old records anew. If you forced me to choose a single favorite GD studio album, this is probably it. (or the other classic from later that year, which I'm actually listening to now, but can't keep up)
BTW, if you like this album half as much as I do and haven't heard the Deadcast season 1 deep dive, I can't recommend it highly enough: https://www.dead.net/deadcast-index