Of course The Wall is a great work of Pink Floyd but perhaps Led Zeppelin IV is better and other competitors are Thriller (MJ)  , In the Court of the Crimson King , In the Wake of Poseidon ( by King Crimson ),Eagle's Hotel California, Beatle's Sgt Pepper's Lonely Heart's Band, Elton John's Candle in the Wind and perhaps Creedence Clearwater Revival but then it does change the genre of the songs   

There's also another Pink Floyd's album Dark Side of the Moon and Jethro Tull...... great songs I must add

debatable