Not all types of sake are supposed to be heated, some types are supposed to be chilled. I have a bottle of each but I've forgotten which one is which.
The normal way to heat sake is to heat some water to just below boiling point in a container then put the bottle in the water for a while. How long you leave it in the water depends on how hot you want the sake to be. Normally you'd heat it in a special little ceramic serving bottle called a tokkuri, but if you don't have one, use the bottle the sake comes in (remove the cap first). The glass bottle may crack if the water is too hot though (glass doesn't react well when it's temperature changes suddenly).
The quick and dirty way is to microwave it, how long depends on how powerful your microwave is and if you're heating the whole bottle or a couple of small glasses of it.
Favourite brand? I'm at work, the bottles are at home and I don't remember their brands. I'm not a sake connoisseur.