which service account to use

Hello Team,

We are setting up Nintex workflows on Sharepoint Online on the O365 tenant.

Some of the workflow actions need to use an username and password. 

We have ADFS setup so the question is for the workflow accounts, do we use a ADFS service account or a cloud "onmicrosoft" account.

Nintex claim that both work but I wanted to understand from our community what account is recommended and why.

Regards,

Ramana