Start on Essentials. Almost everyone should. It covers the things that go wrong and the admin that follows them, and it’s enough for a business where a normal week has no technology in it.
Move to Premium when two things are true. There’s enough happening in a normal week to use a standing hour, and you want the environment watched between visits rather than looked at once something has already broken. If you’re regularly waiting until Friday to raise things that happened on Tuesday, that’s the signal.
Choose Premium+ when you hold data that belongs to other people. Client records, patient details, payment information. The test isn’t how big you are, it’s what you’d have to tell people if a laptop went missing. If the answer to that question worries you, the security and backup work in Premium+ is the part that changes it.
If you’re not sure which describes you, that itself is the answer. Start on Essentials and move when the week tells you to. Nobody is upgraded without being asked.