EzineArticles.com is the grand daddy of article directories. If I would have to choose between 20 so-so and that one, I would have to choose 20 so-so...
Just kidding, depends on what you want to achieve. Are you looking to utilize article marketing to purely build backlinks, or to drive traffic primarily? If traffic, ezinearticles.com will give you the best results since they're the largest.
If you're after backlinks primarily, make some variations and submit to more.
If you already know for which keyphrase you want to rank, then there's no reason to feed the article directories with all that traffic, make your own page and build backlinks to it. Most of the SE traffic that ends up on ezines either goes away somewhere or stays there to browse more. CTRs are not that great actually. But, some of their own traffic might end up at your site, so that's always good.
Another good thing about submitting to more article directories is that your article might be re-published on more websites with a linkback to your site. Plus the traffic of course.
The more article directories you target, greater the chance. It doesn't matter, do-follow or no-follow, mix it all up for best results. Like everything else, you need to know what you're doing and adjust your strategy based on that.