Three-tier Farm install, what to use on DB - SP_Farm or SQL_Admin?

Question

I'm installing SQL on (by example FARM_DB1) server. I created SP_Farm in AD and added it as admin on machines, and I'll use it on WFE's. But what is best-practice for SQL machine? Which account to use better:

• use SP_farm
• create SQL_Service, add it in local admins and install from him
• leave defaults ?

Answer 1

if you ask for the best practice then:

Create the SQL_Admin: The SQL Server service account is used to run SQL Server. It is the service account for the following SQL Server services: MSSQLSERVER SQLSERVERAGENT. SQL Admin on the SQL Server. it should be domain user with Local Administrator on the SQL Server.

read more about the best practice: SharePoint 2013 Service Accounts Best Practices Explained