That's an easy question, renting it out is more profitable because it will become a source of income for you in the future, if you decide to the building you are not been investive and it can't be compared to the income it would generate if that building is on rent but it all depends on your plan and what you want at the moment, most people would rather put their building on rent instead of just selling it out, as time goes on you would make a lot of Profit
How can you rent out if you don't build because the building will not stand on its own without being built or purchased first. In certain places it is true that renting out will make money and even now the owners use the monthly payment method. I have seen several houses rented out with that method and now the owners have many houses to rent out using the money to rebuild. This is a good partnership in making money every month and the potential is very feasible to run.
There are many freelancers or newlyweds who occupy the house and that's what I noticed in the area where I live. But if the capital owned is large, building to sell it will also get maximum profit because talking about the increasing need for houses.