Maybe you want to grow the same type of apples you've seen at farmers markets or supermarkets. Maybe you want to grow the same apple you had when you were a child. Maybe you want to try an apple you've never seen. A few apples won't survive this far north. Some apples turn to mush in our summer heat.
Some apples are very disease resistant and require few if any chemical sprays.
Other apples will not produce a viable crop in Missouri without chemical sprays. Summer apples are great for eating fresh but often store poorly. Summer apples usually don't freeze as well as fall-ripening apples. It takes at least two different types of apple for successful pollination. Crabapples that bloom at the same time as your apple trees work perfectly well as pollenizers.