Your two basic watering cans are either plastic or metal, they also come in a wide variety of sizes and colours.
A plastic watering can will be lighter than a metal can but will unfortunately not last as long as a metal can would. However, with a metal can you will have to take care to not let it rust. You should also take size into consideration as you will be carrying it with a lot of water which will make it heavy. The position of your handle should allow you t carry a full can and also tip it to pour the water out more easily. There is a two-handle design that would be much easier for kids or elderly people.