I like Kerick float valves. Lots of mounting options, simple, lasts a lot longer than the trough floats so cheaper long term. Sold by lots of places, Amazon, US Plastic, etc. Company has been arounf a long time so getting parts in 10, 20 years should be possible.

On a pond I use a water supply comes from a sprinkler valve on a timer. Either tied into an existing line or a dedicated line. I set the timer to turn on for a few minutes each day. So if the float valve fails, and they do, the max amount of water isn't very much.