Hooves have evolved to manage their own moisture balance. Feed the horse well, exercise appropriately, facilitate as natural a lifestyle as you can manage.
Don't waste your money on hoof dressings. Spend the cash saved on hoof boots if your horse needs them, or setting up your facilities so they can live more naturally.
In drier climates you might want to create a natural watering spot, so your horse can wet their feet as they drink, but don't dress hooves with oils, polishes or other products which can destroy the natural moisture balance in the hoof. I have actually seen the outer hoof wall break down from these moisturising treatments.
If your horse gets thrush, then by all means treat it, but don't use anything which you wouldn't put on your own skin. Another horror story - I've seen a horse with chemical burns from a thrush treatment.
Keep your horse healthy, work them hard, let them live naturally, get the hooves trimmed regularly, avoid hoof dressings - you won't go far wrong and you will save a lot of money!