Nine Mail is superb. I use it with Exchange/365 hybrid and an Office 365 account. It's got some great features and is fully Materialised.
It's not cheap, but it's a one off payment and does exactly what I have been wanting without the faff of the official Outlook app or built in Email clients.
Seconded. Been using it for a few months now and it's awesome. Better Exchange integration than Gmail/Office 365 app.