Deciduous magnolias come mainly from cool temperate parts of China and Japan. They are slow-growing but make wonderful specimens in temperate wind protected gardens.
While I usually say you should wait to see a plant in bloom before you buy, the magnolia is an exception as you're better off trusting the picture on the plant label and planting now. If you wait until the usual flowering time in late winter and early spring before you buy the young plant often lacks early vigour because they miss out on that cool settling-in period before summer. Many a magnolia has died during its first summer because it has been planted too late in the season.
Now what are you favourite varieties of deciduous magnolia? Suggestions welcome.