First, Outlook is not only a Mail app. It also integrates contacts and calendars. If you use email to make and accept appointments/schedule meetings on a regular basis, then you'll want to maintain your contacts and calendars in Outlook, too. HOWEVER, Outlook's contacts and calendars do not integrate with Messages/iMessage and FaceTime, so if you're using Messages and/or FaceTime extensively... having your contacts and calendars in Outlook can be a major pain. (And maintaining more than one contacts app and more than one calendar app is just asking for headaches.)
Maybe you'll like Outlook better as a mail app, maybe not. One man's "clunky" is another's heaven. IMHO, "clunky" is the way Outlook does NOT integrate with the rest of the Apple universe.
Both Mail and Outlook offer optimal integration - Mail with the rest of the Mac and iOS world, Outlook with Microsoft's. Which of those worlds is more important to your workflow may help determine which you choose.
If your workplace has an Exchange Server and everyone uses Outlook... that's an excellent reason for you to use Outlook. If, however, you're dependent on iCloud for syncing your contacts and calendars and need very little in the way of integration with your employment environment... Stay away from Outlook - any possible benefits are unlikely to offset the problems. Just because a program comes bundled with Office doesn't mean you must use it in order to get full value from Office.