sequelize seems to be much more popular than slonik. Is sequelize more or less the standard or at least market leader?
https://trends.google.com/trends/explore?date=all&geo=US&q=S...
https://trends.google.com/trends/explore?date=all&geo=US&q=S...
Slonik is much newer, and is Postgres only. But there is a general trend seen in many different projects that support safe SQL execution using tagged template literals in JavaScript, which is a fantastic technology. Slonik was one of the first projects that went this route, but there are now many others.
In general I think it's a mistake to look for a single "market leader" for node DB access. There are many high quality libraries that are favored by different teams for various reasons.
https://trends.google.com/trends/explore?date=all&geo=US&q=S...