The heavy horse. Beautiful. Strong. Reliable. Adaptable. These magnificent animals were vital to the whole economy of the western world until the turn of the twentieth century and played a significant role until the end of the second World War. My own great-grandfather spent his entire working life farming with heavy horses.
Apost-apocalyptic world would need these creatures again. The scarcity of liquid fuels for transport. The lack of engineered machines and materials and the need to move goods, plough land and otherwise rebuild society would place our fate once more on the shoulders of the mighty heavy horse; the once and future king.