Three more...
Wishbone Ash: Argus. I've sampled a few other W. A. titles, but to my ears, nothing else comes close. The fusion of lyricism and power make this an underrated Rock (no-- it's not Prog) masterpiece, IMHO.
Fleetwood Mac: Then Play On. It's a shame that P. Green was losing his grip on reality just as Danny Kirwan was coming into his own but nevertheless, I'd assert this recording comprises the band's artistic peak, along with the Live in Boston recordings. While I very much enjoy Kirwan's work on Kiln House, Future Games and Bare Trees, I much prefer P. Green's playing and compositions to those of J. Spencer and B. Welch.
Janis Joplin: Pearl. I realize there are an awful lot of folks who, preferring the recordings with Big Brother, characterize Pearl as a "sell out" and "too slick". The fact is, Pearl shows off the best singing of Joplin's career. She's arguably less caught up in and hampered by, the "little girl lost" persona and she's singing from a place of greater personal strength, confidence and stability. Her mastery of dynamics, phrasing and vocal technique as means of conveying emotion were never more evident than on these recordings.