Simply select the one that is best adapted to the way you plan to use it
Are you planning to plant a summer annual grass, maybe to boost cattle numbers or to build hay supply? Which one will you plant? It can be confusing because there are six different types of major summer annual forage grasses, sudangrass, sorghum-sudan hybrids, forage sorghum (which we often call cane or sorgo), foxtail millet, pearl millet, and teff. Each one has its own strengths and weaknesses. So base your choice primarily on how you plan to use it.
For example, do you want pasture? Then use sudangrass or pearl millet. Both are leafy, they regrow rapidly, and they contain less danger from prussic acid poisoning than other annual grasses.To read the entire article, link here.