Probably none, they were both massive hits immediately, nobody was calling them failed products months after release.
edit: That said I'm reading now that the early reports that Apple downgraded their expectations for year 1 from 800k units to 400k units after launch were wrong, and instead they were always projecting 400k units.
edit: That said I'm reading now that the early reports that Apple downgraded their expectations for year 1 from 800k units to 400k units after launch were wrong, and instead they were always projecting 400k units.