Can anyone recommend an encryption method for ALL user dbs using SQL Server 2016 STANDARD edition?
There are 3rd party tools which replicate TDE functionality.

I have tested the following during an exercise to evaluate whether we can move from Enterprise to Standard Edition:


https://www.database-encryption.com/
https://netlibsecurity.com/


In both cases, they seem to work by placing a driver between the SQL binaries and the storage layer, and after configuration are transparent to the connecting application. Queries work in the exact same way as for TDE-enabled databases. Once the data leaves the storage, it is unencrypted.  It would appear as an unencrypted database to all authenticated connections.

They do cost, but I believe there are trial versions available.

In performance tests (10,000 small insert queries into a clustered index) I found that DBDefence closely mirrored the performance of a TDE-enabled database. Query times for Netlib increased by approx 8%.  Obviously your specific scenario may differ.

All my tests were performed on SQL 2016 Standard.