Compare the 18-volt cordless electric blower to others of its type. These machines come in a variety of sizes and weights. If they blow with the same force, you clearly wish to purchase the electric blower that weighs the least. Also, you want one that ergonomically suits your hand. You will need to hold the blower for an extended time, and bulkiness can be quite discomforting. Also, the volume of the blower should constitute a factor in your analysis. A loud blower can become very annoying.
Compare the blower to the corded alternatives. Perhaps you can purchase a more-powerful blower for the same price. Yet, you should figure out if the corded blower makes your situation more difficult. If you have a large yard, the cord may not reach all the way around. You may need to purchase extenders and deal with a large amount of hassle just to get access to your entire yard.
Compare the cordless blower to simply raking the leaves. Raking the leaves only costs you the price of a rake. You will burn calories while raking. Raking does not emit a loud noise. If you have the time, perhaps raking manually will be your best option.