If you host your domain on GoDaddy and want to add email with firstname.lastname@example.org, DO NOT purchase their offering of Office 365!
You'll be getting a "watered down" version of Office 365 that (in most cases) is more expensive than buying Office 365 directly from Microsoft. Office 365 Business allows you to connect to multiple domains from one account - whereas GoDaddy's offering creates a new account for each domain and limits your ability to setup "aliases" across domains.
You'll also have access to several of Office 365 applications not available in GoDaddy's basic plan.
And even though GoDaddy makes it trickier to locate, you can still go with basic POP email if you prefer.