Business email on the organization’s own domain, with the mailbox, the sending reputation and the spam handling kept in one place instead of three services that each blame the other when a message goes missing.
Your domain, verified once
SPF, DKIM and DMARC are set up on the page that adds the domain, and every other product reuses that proof.
Search that finds it
Search every folder by sender, subject, body and date, not just the subject line.
No per-seat surprise
Mailboxes come with the organization rather than being counted separately.