What's better: a scanner or a camera?

The answer is... it depends on what you're hoping to achieve.

Batch scanners are fantastic if speed and an automated process is a priority. The batching capability makes it very easy to process many at once without much interaction with the device. The potential problems though are that they can be more expensive and paper jams can occur

Cameras, on the other hand, are fantastic if cost is the priority. You can even use your smartphone to take pictures. However, they require manually taking a picture of each page (unless you have a timer set up) and you will want to set up a copy stand to ensure you take good quality pictures.