Leisure and The Great Escape are BY FAR the most underrated albums.
Also: Instrumentals. Always considered as somewhat second class songs.
Leisure: Everything is underrated except Sing and There's no Other Way.
MLIR: Pressure on Julian, Starshaped, Miss America, Villa Rosie, Sunday Sunday
Parklife: Tracy Jacks, The Debt Collector, Far Out, Trouble in the Message Centre (though I see it getting more love recently), Lot 105. Magic America and Clover Over Dover aren't much appreciated but I don't particularly like them either.
TGE: EVERYTHING except The Universal and He Thought of Cars.
Blur: Song 2 (somehow its popularity makes us forget how fantastic it actually is), M.O.R, On YourOwn, Theme From Retro, I'm Just a Killer for your Love, Look Inside America (don't particularly like it), Movin' On (one of my faves in this album).
13: Am I the only one for whom it's hard to think of this album as separate songs and not as an entity? But I tend to see some songs are more mentioned than these: 1992, BLUREMI, Mellow Song, Trailerpark, Optigan 1
Think Tank: Good Song, Brothers and Sisters, We've Got a File On You, Moroccan etc, and then we've got the controversial Crazy Beat (hate it), Gene by Gene (love it), and Jets (depends on the day XD).