The answer is Elton John.
U2 has only had two songs top the Billboard HOT 100 -- "With or
Without You" and "I Still Haven't Found What I'm Looking for."
Source: Richard Hare, "Charts,"
Adam Sands and Matt McGee, "Discography FAQ," http://www.u2faqs.com/discography/#8.
Elton John has had eight U.S. Number 1's.
Source: Barry A. Jeckell, "Chart Beat," Billboard, 30 June 2005,
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U2 billboard chart singles
U2 billboard chart singles with without you still haven't found
Elton John billboard number 1