There are a number of key variables to consider when you walk into the store and are confronted with a whole line of lawn mowers priced moderately to very high.

Size of Your Lawn - This will determine the type and size of mower that is best for you. It will also be important in your choice of propulsion system.

Engine - Here you are looking at the power (how much horse power?), how it starts, and whether it is a two stroke or a four stroke engine.

Bag Position - This is a function of your preferences when you see the different models.

For some help in understanding the issues go to Choosing A Lawn Mower