Ian Hunter. Both with Mott and as a solo artist.
Don't think I saw anyone mention Holland-Dozier-Holland, yet.
Check out their body of work:
(although interestingly fellow Brummie Denny Laine was perhaps the1st to try to assemble a rock orchestra, including the raver Viv Prince)
Wood shared an obsessive tendency to clone the Spector style with Wilson and Andrew Oldham , spending endless hours like Phil on singles tracks
Jan Berry, prior to his accident, was IMO crafting records that were as novel as his friend Wilson
Ken Hensley. Huge body of work. Also a gifted keyboardist/guitarist/singer.
A different look, at the topic...
Sam Phillips, Guided by Voices, The Bottle Rockets, The Jayhawks, Built to Spill, Dave Alvin, Roy Buchanan, Gillian Welch, Townes Van Zandt, Son Volt, Pavement, Aimee Mann, Freedy Johnston, The Flaming Lips, R.L. Burnside, Drive by Truckers, Vic Chesnut, Bruce Cockburn, Iris Dement, Steve Earle, John Prine, Butch Hancock, Joe Henry, Robert Earl Keen, John Hiatt, Tom Leach, Julianna Hatfield, Mary Lou Lord, Helmet, Richard Buckner, Blue Mountain....I better stop now !
Don't know if he counts as a great song-writer but just watched the amazing documentary on the singer Sixto Rodriguez, Searching for Sugarman, up for an oscar, well worth tracking down.