Investor buyers, who make up most of the market for income property, want to see the building cash-flowing from possession day. A vacant unit forces them to model rent-up risk and vacancy loss before they can qualify the deal, and that uncertainty usually shows up as a lower offer rather than a higher one.
The exception is a building bought by an owner-occupier who wants to live in one unit and rent the other. In that narrower case vacant possession of at least one unit matters more than the rent, and marketing should target that buyer specifically rather than the investor pool.
Whichever way you list, the leases, deposits and rent roll need to be accurate and current, since a lender reviews them closely on income property. Joel Dyck's hand-reviewed valuation prices the building both ways so you can see which buyer pool actually pays more for your specific property.
Get your hand-reviewed valuation from Joel Dyck.