Let's face facts: unlike other categories, there are very few true contenders here apart from Express. Although Meteor did manage to generate a lot of awareness over the years, it sadly seems like it wasn't quite able to capitalize on it.
Per-library survey results.
Number of Libraries Used
How many different libraries are developers using (defined as respondents who picked “have used before and would use again”)?
On a scale of one to five, how happy are developers with the current state of Back-end tools?