People said tablets will replace laptops as far as all-time productivity and work needs are concerned. That has not happened so far. However, the iPad Pro tries its best to become a laptop substitute, but for that to happen, you need a good keyboard attachment. That being said, you need a keyboard case only when you need to attach the keyboard to the iPad pro for long durations.

Experts suggest bluetooth keyboards are preferable over attachable keyboards. 

Before you buy a keyboard and a keyboard case, consider the extra bulk factor too.

The best 12.9-inch iPad Pro keyboard case: Apple Smart Keyboard for 12.9-inch iPad Pro (slim, expensive)

Best keyboard case for the 9.7-inch iPad Pro: Apple Smart Keyboard for 9.7-inch iPad Pro (slim, light, expensive)

The best rugged keyboard case for the 9.7-inch Pro: Zagg Rugged Book (thick and heavy)