Content is definitely more important now than it used to be, but you are going to have a hard time ranking even an easy keyword if you simply place one good article on your site and do nothing else!
Content and link building go hand in hand, have good quality content on your site and you will rank faster when you start building backlinks. Put up crappy, non-readable spun content and you will probably never rank no matter how good your backlinks.
There are of course plenty of other factors to consider too...there are many reasons some of the sites you mention may be ranking higher even though they have less content - things like on site optimization, domain age, domain authority, QUALITY of the backlinks, link diversity, link profile etc etc....all play key roles in how well your pages are going to rank compared to your competition.
One strategy we have found to work over and over again, is adding GOOD QUALITY content to your site every few days BEFORE you start your link building campaign. And when you do start building links, make sure you use good quality content for them too...