Those taking care of my dogs while I work (crazy teenagers!) are not diligent about giving them water. I really think I need one of those automatic watering gizmos.

Which one is best? Also, which ones to avoid?

Thanks.

Indoors or outdoors?

Outside

My dogs use a LIX-IT. It attaches to the faucet head and the water is always on. No fuss and no muss. It didn't take them long to learn how to use it. I paid < $10.

My out side yard has the metal horse brand and works great.
Once a day I clean it out and it stays fresh, they can not get to the float and it hooks right up to a water hose. I have it attached tot he fence so the hose is not accessible.
I also have a short water trough for the dogs to play in, so there is always to forms of water available.

I have used and loved The Waterdog. It is fun and really works well.