There is no single piece of music by Brahms that is more 'famous' than any other. This type of question is impossible to answer. Some pieces of music may be best known in certain countries, while other pieces will be better known in other countries. Some music becomes famous through live performances, some through recordings, some through being used in TV advertisements, and so on. Some music is well known to professional musicians but not to the general public - and vice versa. There are so many variables that there is really no point in asking the question.
A more sensible question would be 'what are some of Brahms's most famous pieces of music?', and answers to that are already available on this site.
Johannes Brahms (1833-97) promoted many up and coming composers in his personally published music journal. the most famous composer that was touted by Herr Brahms, was the incomparable Robert Schumann (1810-56) .
Scott Joplin is most associated with ragtime music. One of his most famous pieces is 'Maple Leaf Rag'.
Schumann was a German composer of the romantic period, most famous for his piano music and his songs, which are both still widely performed. He was also a music critic who identified the genius of Johannes Brahms early on.
Brahms's most famous piece is the Lullaby, but Hungarian Dance No. 5 is pretty famous too.
Scott Joplin is most associated with ragtime music. One of his most famous pieces is 'Maple Leaf Rag'.
Folk music. One of his most famous pieces was "This Land is Your Land".
Brahms' Hungarian Dance No. 6 in D major was originally published in 1869. It is one of the most popular pieces from his set of Hungarian Dances, which were inspired by the music of Hungarian folk tunes. The dances were composed for piano four hands and later orchestrated by Brahms himself.
His famous works are: Piano Concert No. 1 in D Minor Piano Concert No. 2 in B-flat Major Symphony No. 1 in C Minor Symphony No. 3 in F Major (3rd Movement) A German Requiem Violin Concerto in D Major Hungarian Dances Variations on a Theme by Paganini His Lullaby
Five pieces of music written for the clarinet include Time Pieces for Clarinet and Piano by Robert Muczynski, Clarinet Concerto in A by Mozart, 3 Clarinet Concerta but Cruseel, 3 Pieces for Clarinet Solo by Igor Stravinsky and Clarinet Concerto No., 1 by Carl Maria von Weber,.
I would probably say Fur elise by Mozart
the marriage of figaro magic flute don Giovanni
His three most famous pieces would probably be the Brandenburg Concertos, toccata and fugue and Air on a g string amongst others.