Securely transferring confidential payroll data from Payroll (not HCM) to EPM cloud?

Greetings!

We want to load Actual data from ADP (payroll system) to EPM workforce planning, but in a secure way.

What are the ways of securely transferring confidential payroll data to EPM cloud?
I can think off

1. REST API,
2. EPM integration Agent,
3. OIC,
4. old classic way of SFTP - EPM Automate
5. token generation in Gen 2; Encryption at source and decryption at target.

Want to understand the best practices, pros/cons of the various options and real life examples that we use in live projects!
Thank you!