Here's a list of the main benefits of Migrating from Exchange to Office 365:

Easy access from anywhere. Exchange Online allows anyone to access his/her e-mail mailbox from anywhere and from any device: you won’t need a VPN or a fixed device, since any user can easily configure their smartphones and tablets or access their email on any web browser. If "web clients" are not your cup of tea, you can use the MS Outlook client which is natively available for Windows, Mac, Linux, Android, and iOS.

Reliability & Available Anytime, granted by the 99.9% up-time granted by Microsoft's multiple data centers across the world.

Single-Sign-On (SSO). Exchange Online allows to integrate your on-premises directories, thus providing your users with a common identity to access both cloud and on-premises resources.

Large Mailboxes & Emails. 50 GB mailboxes, 150 GB archive mailboxes and 150 MB email sizes.

Real-Time Collaboration using MS Teams, MS Calendar and Office 365 groups native integrations.

In-Place Archive. The "archive mailbox" feature allows any user to archive his/her old e-mail messages using a dedicated mailbox which works in the same way of the primary mailbox and has all the built-in features (including full-text search).