There are mods like Vanilla Apparel Expanded or Vanilla Furniture Expanded that add automated cremation pits or industrial incinerators. You simply set a zone, and the machine burns anything placed in it automatically.
Do not keep the crematorium on 24/7. It uses 200W idle and 700W working. Create a switch or use a Power Logic system (or just micro-manage by drafting a pawn to switch it on when the corpse pile hits 10). Alternatively, install the crematorium inside your freezer. If it’s cold, bodies never rot, and you can cremate at your leisure without power waste.
It’s clean, indoors, and doesn't care about the weather.
With the Ideology DLC, the definition of "best" changes based on the colony's memes.
The major weakness of this strategy is weather. Rain and snow extinguish fires, rendering this method unreliable in biomes with frequent precipitation (e.g., Temperate Forests). It is highly effective in Arid Shrubs, Deserts, and Extreme Deserts.