As per my view back links mainly matters for the Google as compared other search engines link Bing and Yahoo, they works on different ranking algorithms. Back links are important but not the only important thing in SEO there are so many other things which also matters in getting top ranking.

a website is almost useless without quality backlinks.

Keep adding quality content to your site besides obtaining do follow links from high page rank sites.

SEO is better because it is cost effective and good for the promotion of the site all over the world.

All are the best sources to generate good back links and targeted traffic to you website. Also try out other of page SEO like forums, blogging, article submission, directory submission, social bookmarking, document sharing, press release submission that why seo is better.

Targeted Traffic and better business,,,,,,,,,,,