How reliable are the following methods to treat hard water for home use?
Magnetic and electronic water softening devices do not reduce the level of calcium, magnesium, etc in your water. Don't waste your money on them. 

Resin water softeners that require salt are the best way to continually soften all of your water.

Technically it's not the only way, a reverse osmosis membrane can also soften water, but typically not in the quantities needed without getting very expensive. A few gallons a day for drinking is usually the limit. I use RO water for the rinse cycle in my dishwasher, but I'd never be able to generate enough for laundry or showering. 

A good rule of thumb is if the device used to soften the water never sends water to a drain, then it's very unlikely to actually reduce the level of water hardness. Even activated carbon water filters make a negligible difference in water hardness.