I’ll confess that I wasn’t aware that he was still living. I won’t pretend to be knowledgeable enough to be able to rank him among playwrights. He was certainly prolific and successful. He also had a distinct style. If I was watching something, I would find myself saying “this feels like a Neil Simon” or if I found out later that soamethig was a Neil Simon, I would say “oh, that makes sense.”
He was a 'commercial' playwright, and a good one. His plays appealed to that Broadway stereotype of the 'tired businessman', meaning the audience didn't have to invest a whole lot into getting what he was going after. Which often was laughs. I was in a production of 'The Sunshine Boys', which was about an old vaudeville duo getting back together for a payday even though they can't stand each other. Kinda like 'The Odd Couple' with some vaudeville routines mixed in. While he sometimes reached for profundity, he was generally viewed as the king of middlebrow humor.
He was also nicknamed 'Doc' Simon b/c, when a script had problems, he was often called in to fix those problems. A script doctor.