Decide whether you want to deal with a power cord. That's the primary difference between gas and electric leaf vacuums. Larger yards can benefit from a gas leaf vacuum because there's no need to store and unravel a heavy cord; consider that it will need to be at least 100 feet long for larger yards in order to cover the entire area. If range of motion is important to you because of your yard space, a gas powered vacuum could be the answer for you: no rolling up cords, tripping and getting the cord stuck on other items in your yard.
Gas leaf blowers and vacuums are heavier than electric because they include a small engine that's powered by oil and gasoline. The average electric vacuum can be as light as 5 pounds, but the gasoline powered vacuums can be as heavy as 11 pounds. Gasoline vacuums also blow louder because of the engine and as a result burn emissions; the noise and fumes can bother some people. If the environment is what you're worried about, the greener choice is definitely electric.
With the unrestricted range of motion comes a higher price tag for consumers. As of 2011, an electric leaf blower and vacuum combination can be scored for as little as $35. Meanwhile, the average gas-powered leaf blower and vacuum starts at $70 and can peak at nearly $200. Homeowners with a small yards may opt for the cheaper electric-powered vacuum due to the price difference. A heavy duty, thicker gauge cord is necessary to provide the correct voltage to the electric motor. Doing otherwise can damage the motor.
The cost of ownership and maintenance for a gasoline powered vacuum is slightly more than for electric. Beside frequent gasoline fill-ups, the engine will also require occasional oil changes and spark plug replacements. With an electric vacuum, there is no maintenance involved; just plug it in and go.
The bottom line is mobility. If you are concerned about maneuverability and have a large yard, a gas-powered blower is probably a more ideal fit. For those with small spaces who want a cheaper option and don't mind a power cord, electric is far easier to operate and maintain.