The highest price you will get for the property will be from selling it to an owner occupant. You will have to discount the price to sell the property with a long term lease.
I would NEVER allow a leasing broker to sell the property. They will want to sell it at a significantly discounted price to another of their management clients or buy it from you themselves. They often have a poor idea of market value anyway, as sales are not their main business.
In your shoes, I would give the tenants plenty of notice and turn the house over to a competent resale agent with contractors on speed dial when they move out. You will get a much better price for the property.