We are planning to deploy SharePoint server 2016 On-premises and we will also use OneDrive for Business Online as a hybrid approach.
We want seamless user login experience when we redirect users from On-premises SharePoint to OneDrive for Business Online. Does Azure AD Connect with Password Sync will give SSO experience or do we need Complete ADFS Infra. ?
Yes, I did this with my initial deployment starting with OneDrive. They didn't have this seamless SSO to start, but now that they do it's worked fairly well. Long as you update GPO etc. to include the trusted sites and all that, you can get auto login for most Portal sites.