Milk chocolate seems to be the most desired chocolate when dipping strawberries in chocolate. Since dark chocolate has a slightly bitter taste to it, pairing milk chocolate with the sweetness of the strawberries seems logical. Sometimes, white chocolate is drizzled over the tops of the milk chocolate, but this is usually done for appearance and not for taste. Milk chocolate also dries well so it will stick to the strawberries.
However, if you like the contrast between the bitter dark chocolate and the very sweet strawberries, then they may be what you want to use. However, most recipes call for melting milk chocolate chips in a double broiler before dunking the strawberries in. Then melting white chocolate for the drizzle at the end.