Pros and Cons or building condos for sale vs Rentals

[John Barry]

My father owns a piece of property that currently has a triple decker on it. Years ago he started (then paused, now actively pursuing again) tearing down existing building and building a 21 unit building on it. Looking for opinions, feedback, pros and cons to building the building as condos and simply selling them off 1 by 1 or building the building and keeping all units and renting them I have real estate license Any and all input would be appreciated Thanks (01902)