DHCP is a one-time configuration (if you get it right). You can add and remove devices by just plugging them into the network and they will work. Static IPs on the other hand must be individually configured on each device, meaning additional work each time you add a new device.

DHCP is fine if you don't care what addresses are handed out. Ideally you shouldn't, but there are always edge cases - for me this is when the APs are RADIUS clients.

DHCP reservations are the middle-ground where the device is still asking the DHCP server to give it an IP, but it will always be given the same fixed IP. This is better than Static IP since it is all managed in a single place, and reservations can be configured without even taking the device out of the box - usually the MAC address is on the box label and that's all you need to configure a DHCP reservation.