Their songs from the 1970s and 1980s are very familiar to everyone, especially Breakfast In America:

Supertramp combine an excellent songwriting contrast of the two singers Roger Hodgson and Rick Davies, who also both play keyboards. Their styles are different making Supertramp a band with two distinct sounds.
Here is Roger Hodgson singing some of his most famous Supertramp songs:

Here is Supertramp with Rick Davies singing, from the 1980s: