Sybill Trelawney's prophecy said that the child to face Voldemort would be
"born as the seventh month dies."
Neville was born on July 30th, Harry on 31st. So isn't the 31st really the last day of the month, the day the month dies?
Since Harry fits the prophecy better (e.g. he was born on the last day of the month), why would Neville even be considered as the child of the prophecy?