Grated Daikon (Oroshi)

So I really love anything with grated daikon as a condiment, as it is so refreshing and cool on your tongue! It's easy enough to grate a daikon at home, but I noticed that every now and then, I buy a daikon that is kind of really "radishy" tasting, kind of hot and feels like it is burning my tongue. Does anyone know how to tell when I'm at the store how to pick a mellow tasting daikon? Is it better to buy a piece near the root or tip? Does this even matter? Thanks!