Former Mayor David Dinkins, who succeeded Koch, called the former mayor "a feisty guy who would tell you what he thinks."
"Ed was a guy to whom I could turn if I wanted a straight answer," he told on Fox 5 News Friday.
Bald and bombastic, paunchy and pretentious, the city's 105th mayor was quick with a friendly quip and equally fast with a cutting remark for his political enemies.
"You punch me, I punch back," Koch once memorably observed. "I do not believe it's good for one's self-respect to be a punching bag."
His hospitalization forced him to miss this week's premiere of a new documentary about his career. "Koch" opens in theaters nationwide on Friday.
The Rev. Al Sharpton, head of the National Action Network, said in a statement Friday that although they disagreed on many things, Koch "was never a phony or a hypocrite. He would not patronize or deceive you. He said what he meant. He meant what he said. He fought for what he believed. May he rest in peace."
The mayor dismissed his critics as "wackos," waged verbal war with developer Donald Trump ("piggy") and fellow former mayor Rudolph Giuliani ("nasty man"), lambasted the Rev. Jesse Jackson, and once reduced the head of the City Council to tears.
"I'm not the type to get ulcers," he wrote in "Mayor," his autobiography. "I give them."
When President George W. Bush ran for re-election in 2004, Democrat Koch crossed party lines to support him and spoke at the GOP convention. He also endorsed Mayor Michael Bloomberg's re-election efforts at a time when Bloomberg was a Republican. Koch described himself as "a liberal with sanity."