tie for three; sorry im indecisive:
lisa 1 (without it there would be no macintosh--a flop but it paved the way for g5's and everything we know and love about apple), the original ibook (cmiw one of the first consumer laptops, had airport which exploded into an industry standard and is present in just about any modern laptop worth it's weight in plastic), and last but not least: the newton messagepad (among the first pda's, had handwriting recognition, several years ahead of it's time). these products may not have been incredible but they showed apple innovation and paved the way for a lot of the modern computing products we use today.