In order:
Madonna. I have so much Madonna.
Weezer.
The Beatles.
George Straight.
Aerosmith.
ETA: Almost forgot Live.
Speaks to the quality of the people on the Dope.
Here’s my apparent top 10:
[ol]
[li]Beatles[/li][li]They Might be Giants (But the 20 or so 5 second tracks for Fingertips is adding a bit of padding)[/li][li]Ataris[/li][li]Pet Shop Boys[/li][li]Legião Urbana[/li][li]Cure[/li][li]Death Cab for Cutie[/li][li]Daniela Mercury[/li][li]Moby[/li][li]Muse[/li][/ol]
A bit eclectic.
Wilco
Disturbed
Lacuna Coil
Bob Mould (solo artist only - hits #1 if you include Blowoff, Husker Du, and Sugar)
Filter
MC Frontalot
The Hold Steady
Opeth
Sugar
Rock: Rush, Pink Floyd and U2
Pop: Madonna
Peter Gabriel: 8 studio albums, 4 soundtracks, 3 live albums, 2 compilations, 2 foreign language albums, 2 official bootlegs, 2 unofficial bootlegs, 3 singles, various odds and ends (vinyl, cassettes, VHS, DVDs, Blu-rays, single tracks on soundtracks…)
Genesis: 15 studio albums, 2 live albums, 5 boxsets, various DVDs, a studio bootleg recording
Pink Floyd: 15 albums, DVDs, various odds and ends
Honourable mentions: Tom Petty, Kate Bush and Yes, any of whom may outrank the above three if I bothered to count it all up.
No idea, but I would suspect it’s Chet Baker, Duke Ellington, Ben Webster or Miles Davis.
Swoon. He’s just got the best breathy attack doesn’t he? As light as Baker’s but you don’t hear the drugs.
On my computer - Tom Waits
Vinyl - (started collecting in 1967) Herbie Mann
Ha! I had to look up the spelling of vinyl. (and it still doesn’t look right)
Appropriate username 
I wonder if they’re gonna do another Neverender and if so what order the albums will be in, since at least the 5th one was a prequel in the storyline.
Yes, I do! I heard they made 2 versions of that cover. One fuzzy and one smooth. I got the fuzzy one.
A smooth one? But what’s a macho flautist if he’s not hairy?!
The variety here is fascinating.
Like others of my generation, my owned music spans a wide variety of formats. And now my digital collection includes everything my kids like, too. For sheer quantity, the “artist” we own the most of is the Glee Cast.
I used to buy everything Billy Joel put out, loads of James Taylor, CSN(Y) in their various incarnations, and I inherited a large Beatles collection. That’s my personal top tier. Levels below that would be Five for Fighting, the Plain White Ts, Indigo Girls, Richard Shindell.
All the rest is just a couple of albums by each artist.
I have more albums by Tom Waits than anyone else. No idea how many tracks that adds up to.
I just recently got around to finally ripping the last of my CDs into iTunes, so it was pretty easy for me to count this up. Two artists dominate my collection. Nobody else even comes close:
They Might Be Giants (198 tracks)
Ben Folds (96 tracks, includes both solo stuff and Ben Folds Five stuff, plus the album he produced with a cappella college groups covering his songs)
Going by # of albums…
21 - Bob Dylan
19 - Little Feat
16 - Beatles
16 - Jimmy Buffett
15 - Rolling Stones
13 - AC/DC
In terms of number of albums by artist:
13 - Bruce Springsteen
11 - The Beatles
11 - REM
8 - The Who
7 - Bob Dylan
7 - U2
6 - The Rolling Stones
In terms of plays on my computer since July 2005:
The Beatles - 1,540
Bob Dylan - 1,156
The Rolling Stones - 976
Elvis Costello - 951
Otis Redding - 575
The Who - 548
Bruce Springsteen - 527
The Kinks - 520
Neko Case - 504
U2 - 473
James Brown - 468
the Beatles
Leon Russell
Todd Rundgren
a patchwork myriad of others
To my credit (?) I never bought an 8-track.