All have a certain value in comparison, but you'll want to focus mostly on the airflow statistics. If you're only going to be dealing with dry dirt and small debris, a less powerful machine that will reach 110 to 125 mph and 300 to 350 cfm will probably be sufficient. The biggest selling point of gas-powered blowers is their portability. There are no cords to hassle with, so you'll be able to move comfortably around your lawn without trampling flowers or getting caught on sprinkler heads. It should also be noted that gas-powered blowers have come under scrutiny in recent years because of noise and pollution concerns.
Electric blowers are the lightest and quietest of blowers available.
You'll find a wide range of power options, with typical machines producing airflow between 110 and 200 mph. Electric blowers are easy to start, require no fuel or oil, and, in general, are more reliable than gas models. The only real drawback to electric models is that they need extension cords. A good rule of thumb on deciding which type of blower to buy is to determine whether you'll need more than a 100-foot extension cord to reach all the areas you want to clean. If you can't do it with one 100-foot cord, consider a gas alternative.