i prefer toro and exmark for a couple of reason. mostly because i've come to know them as good quality machines that deliever a good quality cut.
i started with them because of the price and available. there is only one dealer in my neck of the woods that carry scag, walker and wright. the other 4 dealers do exmark, toro and john deere. the other brands in the market like dixon, bobcat, gravely, grasshopper, etc aren't even available.