1. Stevie Wonder (well over 2,500 songs, though some are duplicated from Greatest Hits packages and the like)
CDs I own:
I Was Made To Love Her
Down To Earth
For Once In My Life
My Cherie Amour
Music Of My Mind
Talking Book
Innervisions
Fulfillingness First Finale
Songs In The Key Of Life
Journey Through The Secret Life Of Plants
Hotter Than July
Woman In Red Soundtrack
In Square Circle
Characters
Jungle Fever Soundtrack
Conversation Peace
Natural Wonder
Live In London 1995 (A Night of Wonder)
Definitive Collection
Song Review
A Time To Love
Live Albums (Bootlegs)
Live At Finsbury Park (Funkafied Rainbow) - 1973 (I think)
Live At Berkeley - 1973
Wonder-Dream Concert - 1995 w/Bob Marley & others
Secret Life Of Plants Tour - Pasadena, CA - 1978
Live At The Forum
Live At The Roxy
Live At The Circle Star Theatre
Live In Atlanta 1988
Live In Pasadena 1988
Live From Budokan - 1982
Live From Budokan - 1988
Natural Wonder Tour - Madrid, Spain 1992
Natural Wonder Tour - Boston, MA 1995
Baltimore, MD - 1998
2005 - Abbey Road Studios (Soundboard)
2007 - Chicago, Ill
2007 - Glendale, AZ (Phoenix)
2007 - Grand Prairie, TX (Dallas)
2007 - Montreal, Canada
2007 - Uncasville, CT
2007 - Los Angeles
2008 - Holland
2008 - Paris
2008 - Los Angeles
2008 - Boston, MA
2008 - Concord, CA
In additon, I have DVD rips of audio, and iTunes' 579-track Complete Set, which includes all the official releases plus many rarities, remixes, alternative versions & more.
2. Michael Jackson
3. Jackson 5/Jacksons
I don't need to go over all of the official releases, but I've got all of MJ's normal stuff (Off the Wall, Bad, etc.) plus I've got a few boots of MJ, I've got a few compilation sets, several J5 albums and The Jacksons (self-titled), Destiny, Triumph & Victory. I need to get Goin' Places and 2300 Jackson Street yet. I've got quite a few MJ boots as well, and some audio rips from some of the bootleg concerts.
4. R. Kelly
I'm not nearly as high on his recent stuff as I am his work in the 90's, but I do love R. Kelly's good stuff. Most of his output in the 90's was stellar and he definitely new how to walk the line between old-school and new school. At some point in the last five years, he fell off the wire and landed on the new-school side. What a shame.
5. Prince
I don't have much of his older stuff, as I've never really cared for it. I've got some stuff like Purple Rain, 1999, Batman Soundtrack and Sign O The Time, but I really only like about two tracks on Sign, which is one of his most praised albums. I prefer some of his bigger 90's hits and his more recent work. I like the Emancipation album quite a bit, as well as his three most recent albums (Planet Earth, 3121 & Musicology). A lot of his live recordings are fun too, I have probably 5 or 6 good boots of his. I'm sure people who are deep into Prince probably have 25,000 tracks of his, the guy has done a LOT of shows and had a LOT of recordings.
Those are the main ones. I'm not sure where I'd go from there, but I'd imagine I have quite a few John Legend tracks as well.