A good plastic watering can is one of those gardening tools that can be very useful in the garden every day. While I love cute little watering cans and fancy metal watering cans, my plastic watering can is the one that gets the most everyday use in the garden. Plastic watering cans are usually quite large, holding one to two gallons of water. They also tend to have high-flow nozzles that deliver water faster than watering cans with metal wreaths/spouts.
A good plastic watering can should have a removable nozzle. That is, the tip of the nozzle (where the small hole is at the round end) should be removable. Most plastic watering cans have a friction fit removable nozzle tip, but oddly enough have a threaded swivel nozzle. Both are great if the nozzle tip stays on when you want it to and comes off easily when it needs to be cleaned.
Plastic watering cans should also be quick and easy to fill. Look for a model with a hole large enough that you can easily fill the watering can with a garden hose nozzle. This is easiest if the hole is large enough to insert the nozzle end of the hose directly into the watering can to prevent overspray when the hose is on a stronger nozzle setting.
Finally, look for a watering can that is portable. Choose a plastic jug that fits your body and is ergonomic to carry. An oversized jug or awkward handle can make using a watering can no fun.