U2 has been and still largely is the most consistent band/artist act for quite some time now. Almost everything post Joshua Tree could qualify as "famous". It would be more fruitful to compile a list of their material that isn't well known.
Not well known
Joshua
Exit
Mothers
Rattle
Hawkmoon
Love rescue me
when love comes to town
freedom for my people
Achtung
so cruel
trying to throw arms/world
ultraviolet
love/blindness
Zooropa < aside from U2 fans, largely unknown material
zooropa
babyface
somedays
last time
wanderer
pop
everything's either been sampled or remixed
ATYCLB
grace
wild honey
HTDAAB
man/woman
love/peace
one step closer
Give or take a few, practically 1 in 4 U2 songs elicit a "that was by U2?" reaction, whenever they're informed.
But, to answer your question, I'd reckon it might be "one" - it's got universal appeal across all sorts of genres.