Apart from, as every post above yours says, the fact that directory submission is virtually useless for SEO these days, one thing that's important to remember if you do insist on giving it a go is that PageRank is calculated by page, not by site. So a directory might have a homepage with PR5 but if your link is going to appear on a page with PR1 along with a thousand other links, how much do you think that is going to be worth? Not much. And the chances of finding this mythical beast, the directory site with dofollow links, high PageRank on all pages and a small number of links per page and one that will accept every one of your submissions are near enough nil. If such a thing did exist even briefly, it would be overrun with spam within an hour, and would cease to have the quality that it needed.