The popular oscillating sprinkler, with its metal or plastic tube that moves back and forth, is a good choice for watering rectangular lawns. Better models have an adjustable spray pattern, at least 15 spray jets to ensure proper coverage and a metal filter in the hose connection to prevent clogging.
Stationary sprinklers, including ones with rings and salt-shaker patterns, are designed to water in a proscribed pattern over a fixed area. Fixed sprinklers with metal frames are more durable than plastic and better models feature interchangeable spray turrets to vary the watering patterns and a hose connector with a metal filter to eliminate clogging.
Rotating sprinklers have two or more arms that disperse the water in a complete circle when they spin. Better ones have a heavy duty, non-tipping metal base, emit droplets rather than mist for less evaporation, and have a metal, rather than plastic, swivel coupling. A series-connection base allows several sprinklers to be strung together along a line of garden hoses.