There's a reason "This Town Ain't Big Enough for the Both of Us" was so popular and is still their best known song.
Its album Kimono My House is also one of the band's finest overall, effectively combining Glam Rock with various disparate influences altogether into its individual songs. The next two followups are equally good.
No. 1 in Heaven managed to combine the best of the band's humor, cleverness, and gravitas with Giorgio Moroder's signature Synth-Disco sound, making another one of the band's best and most fully-realized records.
You could make a pretty good argument that all of their 70s output was their best.
Gratuitous Sax and Senseless Violins was a stellar Dance, House Music-influenced comeback from the stagnant Synth Pop music the band had put out the previous decade. "When Do I Get to Sing 'My Way'" is one of the band's best dance singles.
Lil' Beethoven is a magnificent Deconstruction of the Pop music format.