According to writer Brian Garfield, Sidney Lumet was set to direct the film with Jack Lemmon playing Paul Kersey (presumably to be more in line with the “everyman” character in the book) and Henry Fonda as the police chief.
What if Sidney Lumet had directed Death Wish?… The Result:
Sidney Lumet would never have chosen to direct the far-superior Serpico (1973).
Serpico is hailed as a minor classic. Pacino’s performance in the movie is widely considered as one of his best. His role as Frank Serpico is ranked at #40 on the American Film Institute’s 100 Years… 100 Heroes and Villains list.
In Wes Anderson’s film Rushmore Max Fischer would have never written and directed a stage version of the film Serpico, complete with a climactic shootout.
Audiences would have never been treated to the It’s Always Sunny in Philadelphia episode “Bums: Making A Mess All Over the City,” where Charlie Kelly imagines he is an undercover cop and refers to himself as Serpico.
The movie would have been shot in black-and-white.
The world may have never known Denzel Washington, nor Jeff 
Goldblum, who both landed their first feature film roles.
Sidney Lumet, being a much more talented filmmaker than director Michael Winner, would most likely make a better film and maybe even attract the attention of the Academy of Motion Pictures and Arts.
The film would never have spawned four sequels, including the completely over-the-top Death Wish 3, a.k.a. “the single guiltiest pleasure ever put on screen.”
The film was a watershed for Charles Bronson. Bronson became an American film icon who experienced great popularity over the next twenty years, including the film’s four sequels. Bronson would never have become a leading actor, nor would he have found himself as an action movie icon.
Multiple Grammy award winning Jazz musician Herbie Hancock would have never produced and composed the original score for the soundtrack to the original Death Wish movie; a score that is still regarded among one of the best in 70’s action films.
Death Wish remains a milestone in cinema history, considered the first urban film to depict a civilian taking up arms against criminals. While this concept existed in many previous westerns, Death Wish was the first to place it in a modern setting. The film had unexpected resonance in cities like New York and Los Angeles, where crime had reached incredible levels during the early-to-mid 1970s. Moviegoers applauded Kersey whenever he shot criminals down and cinemas enjoyed record ticket sales during the movie’s first run. I doubt the presence of Jack Lemmon in the leading role (although a much more talented actor) would allow the film to have such an impact on viewers.
– Kyle