I'm a fan of Mick Ronson and I think the first four Bowie albums with Mick Ronson are great...the 5th and final (Pin Ups) is not!
The Man Who Sold The World - A bass heavy, guitar riff album that has stood the test of time for me. Must hear "All The Madmen", "Running Gun Blues".
Hunky Dory - A singer songwriter album with piano by Rick Wakeman. Must hear "Life On Mars?", "Changes".
The Rise And Fall Of Ziggy Stardust And The Spiders From Mars - The perfect blend of the previous two albums at the right moment in time. Must hear "Ziggy Stardust", "Moonage Daydream".
Aladdin Sane - This builds on Ziggy with lots of window dressing but as a whole takes a step back. Must hear "Time", "The Jean Genie".