"Rock 'n' Roll is just a toothless old woman" (Bowie 1975)
Is rock dead?  The Beatles are no more, Stones in trouble, Zeppelin fading...Why not make a R&B album!  A diversion from his previous styles, Young Americans, RCA APL1-0998, released in early 1975 produced some great hits in the title track song and Fame. I think this album shows Bowie's diverse talents and attraction to various styles of music, which is demonstrated again and again through his career.
Here is the funky song Right followed by Fame 

From 1976 come an album of great experimentation. With R&B & electronic influences, Station to Station is considered by many to be one of Bowie's Masterpieces.  A must have album for any Bowie collector, this is a beautiful, cohesive album. Lyrically it is a very personal album and perhaps has Bowie speaking of his connection to God, especially in Word on a Wing.  This is his cover of Wild is the Wind (written by Dimitri Tiomkin & Ned Washington in 1957). Superb vocals.

Changes One Bowie is a greatest hits album released in 1976 and would be a good album for anyone who doesn't have much Bowie music in their collection.  This has many great songs from 1969 through '76. as well as the previously unreleased song John, I'm Only Dancing.
Hard to go wrong with this choice.  RCA APL1-1732.

The first album of the "Berlin Trilogy", Low, was recorded in Berlin when Bowie was attempting to quit cocaine. This album took a while to grow on me, it is so different and not cohesive at all; but it is now up there with my favourite music. In collaboration with Eno and sharing an apartment with Iggy Pop at the time, the album is another experimental album with Eno playing moog synthesiser on many of the songs.  The two sides are like two different albums, with the first side having many short rock songs and side two mostly instrumental moody spacey music; again nothing like Bowie's previous works.  For a stark contrast here is Be My Wife from side 1, then Art Decade from side 2.

Jumping ahead a few years to 1983, comes Let's Dance, the last David Bowie album in my collection.  This is a pop album, which produced some huge hits with Let's Dance, China Girl and Modern Love, and I believe this is his most successful album financially.  This album also features the legendary guitarist Stevie Ray Vaughn on lead guitar!  Which in itself is interesting having a blues guitarist on a dance album!  It is a good album, great pop songs, but not my among my favorite of Bowie albums, a little too commercial.  This is his first album with the new label EMI. (SO 17093)