It depends on how people are going to view them. And if they are standard or high-def videos.
But probably the best quality-to-file-size is Publish & Share/Computer/AVCHD with the YouTube SD or HD preset.
BTW, as I'm sure you know, your customers will only be able to download your video in the format you post if you've got your own FTP site. If you post your videos to sites like Vimeo or YouTube, they will be re-encoded and reformated by the site.