You might know, that the support policy for SharePoint and SQL Server has always been
N, N-1, N+1
That means that for SharePoint 2016 the supported versions of SQL Server are SQL 2016 (N), SQL 2014 (N-1) and SQL 2017 (N+1) – which means a database compatibility level of 12 or higher. But when reading this knowledgebase article and Stefan Gossner's blog, it turns out, that selecting a database compatibility level of 11 (SQL Server 2012) is beneficial for the performance of the SharePoint farm. Compatibility Level 11 it is!
My thoughts and findings about SharePoint 2016/2013/2010 and SQL Server