Microsoft 365 E5
The top enterprise plan, bundling everything in E3 plus the full Defender security stack, advanced Purview compliance, Power BI Pro, and Teams Phone.
E5 is worth buying when you will genuinely use most of what it contains. The straightforward test is whether you need both the full Defender stack and advanced Purview compliance. If you need one but not the other, E3 plus that single suite usually costs less.
Buying E5 and enabling a fraction of it is one of the most common and most expensive licensing mistakes, because the unused capability is invisible on the invoice.
Where this comes up
Microsoft 365 E5 sits inside our microsoft 365 and cloud work. If you are trying to work out what this means for your own environment rather than in the abstract, that is the page worth reading next, and a short call will get you a straight answer faster than either.