It really depends on personal circumstances and the quality of furniture that´s is being included. In certain cases it can be a strong negotiating tool to close a deal if it is not included in the sale price.
In some cases, for instance, when a similar property is being sold in the same complex and the value of both properties is similar, considering the one that includes furniture gives the idea of obtaining a better deal than the one that does not.
On the other hand, if the furniture is included in the sales price of the home and the prospective buyer does not want it, they will expect a larger discount for not including the furniture in the deal.
Pro Tip:  Don’t expect home buyers to pay nearly as much money as the buyer of the furniture included in a deal has paid, even if it has only been used for a very short period of time. Consider that requesting extra money for furniture can be a deal breaker, although including it can give you some leverage. It is always best to let the buyer make the first move in the form of a formal offer.