It is best to focus on both along with other factors, but just focusing on content and backlinks will not yield results as desired.
When you publish an article, no matter how great it is in your eyes, at last it is nothing unless you get potential visitors and still that article is of no worth unless you make your visitors share that article.
In reality, the power of any content does not depend upon the backlinks it has or the large it is, but the share it has socially in the marketing. It is one secret logarithm used by google to determine how much that article is getting favored by visitor especially unique ones.
But getting visitors to share your article or anything related to it, does not effect much it's rankings in SERPs. There comes the factor of back-linking
Backlinks is the first algorithm used by Google to determine the content, not the whole website. Thus it is huge. Getting backlinks is more important in maintaining the position of your content is SERPs or rising it. Just getting huge visitor's from referral sources and indirect sources does not effect much the rankings in SERPs.
A good visitor acquiring strategy is that which focus on all factors rather then just two and for present as well as for future. The content should be first available to the general public and then later the should be focused on backlinks.
Take example of backlinko, Brian builds some backlinks in advance as the article rolls on, but foremost focuses on content and later focuses on backlinks.
Content does not last long, this is where backlinks comes into effect to maintain the article integrity in search engines.
But at last, nothing will give results if the content is not up to reader' expectation.