One of the newest iPad Pro models.
* Fastest transfer speeds for external devices.
* Best screen for editing, and viewing
* Best Apple Pencil support (again for editing)
* Best camera, if you're forced to use it as a backup.
Size would depend on your eye sight, and how big a device you want to hold in your hands. Get all the storage you can afford. At least 512 GB.
That said, the newest iPad Air model is pretty good, if you want to cut corners.
Keep in mind I'm just an amateur, or more like a dabbler. But I do watch a fair number of iPad related tech channels, and this is more or less what they say about video and photo work. More video than photo, but if it is good for pro video creation it'll kill photography.
