There is no doubt that iPad is king of the tablet world and I enjoy using mine, but for my business companion device I have found a refurbished Microsoft Surface 2 with the Surface Type Cover 2 keyboard to be my favorite. Since I am running a 32 GB unit, I leverage a 32 GB microSDHC card for additional space (cannot do this with an iPad). Security is critical to my business and my main drive is encrypted since I leverage a Microsoft account to login. The microSDHC card is protected with BitLocker To Go (requires access to a Windows 8.1 Pro system for initial setup).
The display is full 1080P HD, and looks amazing. The unit gets a bad rap since it is running Windows RT, but since RT cannot install traditional Windows apps, the attack surface is much smaller. I feel very secure running this as my companion device, especially since Microsoft will provide security support for Windows RT 8.1 up to January 2023.
The unit comes with Office 2013 RT, but is limited to non-commercial use. Because I have an active Office 365 E3 subscription, I am able to use Office for commercial use. My favorite modern UI app is the calendar, which allows me to quickly see all of my personal and business appointments in a easy to read single view. I elect to only run my business email through Outlook, and my personal accounts through the built in mail app.
Performance is very good for an ARM processor with 2 GB of memory. A refurbished Surface 2 can be purchased for $200, and add another $80 for the Type Cover 2 keyboard. You can always add a larger microSDXC card to carry all your favorite movies and music along too...