jerrydf
It has to be Brian Wilson.  Also that other guy Traditional.

HUGE Brian Wilson fan.
 
And Mozart.  Tchaikovsky as well.

Okay, since we're talking composers and not songwriters, I'll defer my Paul McCartney suggestion.
Classically speaking, I'm partial to Beethoven, then #2 Gustav Mahler . . . they captured the most extreme ranges of emotion in their respective eras. More recently, it has to be John Williams . . . because his amazing range of music for film in the contemporary era is bound to be classical 100 years from now.

Although I am not classically trained myself, my all-time favourite composer is actually one of the classical greats, Joseph Haydn (1732-1809). He pioneered all the "tricks" that arrangers and producers now use when structuring a song to keep it interesting, taking into account the listener's anticipation and expectation of what is coming up next.

Why couldn't Mozart find his mentor?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Because he was Haydn

I like Holdsworth, Satriani and Steve Morse for their guitar compositions...Pat Metheny and Lyle Mays overall and Hans Zimmer

Kamikaze
Why couldn't Mozart find his mentor?
 
 
 
Because he was Haydn

Good one...

There's a difference between a composer and a song writer.  One is more utilitarian than the other (serving the audience.)  Of course most of the big composers wrote for an audience as well, and all of the greats composed songs.  They had different hats on during those times  (IMO TAKE IT WITH A GRAIN OF SALTZ)  Please don't post obscure quotes which have been removed from context! I'M NOT LOOKING FOR A WILLY WAR!

 
Glenn Miller.

Handel – Everything
Sousa – Memorable Melodic Marches
Tchaikovsky – The Nutcracker
Saint Saens – Symphony # 3
Brahms – Symphony #4
Beethoven – Piano Sonata # 8
Elgar – Pomp and Circumstance Marches 1 – 5
Elgar – Enigma Variations
Bach – Almost Everything
Boyce and Hart – I Wonder What She’s Doing Tonight
That’s a start.
 

Are songwriters not composers?  What is the distinction? Its all music, just different styles and types.
 
Frank Zappa would embody both since he wrote songs and so called "serious music", a term he himself hated. So is he a composer when writing one type of music and a songwriter the next, and if so when does it change?  Keep it simple and call them all composers.
 
Anyway, cant really call them favorites because the list is almost endless. I like so much different stuff. 
Bartok, John Williams[<font]. Bill Evans, EST, Jaga Jazzist, Mats & Morgan, 80s metal/rock, Springsteen, keith Jarret, Warren Zevon, Ennio Morricone, Frank Zappa, Calvero, Radiohead, etc etc etc forever and ever :) 
 
There is good music in every genre I am sure, just  matter of finding the good stuff.