Both are important.
Think about it: you want to get a city by your car. What do you do? Of course, you will watch the road-signs. These signs lead you out into that city. You get to that town and look around: whether you like to stay or will be better to go away. You'll see the main square. Deciding whether or not you like to be there. And you are acting accordingly, stay or go away.
Turn off the above story into the case of the content and backlink of a website. The road-signs are the backlinks, helping visitors to reach the town alias your website. Visitors arriving to the main squere alias to home page of your website. Visitors see your content at that page. If they like what they see then probably spend more time on that page.
What induces them to stay longer? If the content resonates with their interest. Finding garbage content they will go away in 2-3 seconds. Finding quality content they probably stay longer and read what you say to them.
So, having many and quality backlinks means your website get quality visitors who could be potential buyers by reading your quality content.
I hope this helps you to undertand the importance of factors you asked.