"An apple a day can keep the doctor away." Wow, I sure wish this were true, but no cigar.
There is little truth with this phrase, but probably the biggest advantage of eating apples is its taste. However, the variety of that apple can make a great difference to your palate. But, variety isn't the only factor to consider, especially if you desire to plant an apple tree or two around the house. With the price of apples in the market, that might not be a bad idea.
You need to consider the size of the tree that you can manage; and size is determined by the the rootstock or that variety it is grafted onto. What you don't want to do is to produce an apple tree from seed or have a tree without a specific rootstock because you will need a hook and ladder fire truck to pick those apples.
Today, apple trees are grafted onto several different rootstock, or that part of the tree under the ground. This can help guarantee the tree size the homeowner desires, not to mention when that tree will start to produce.
Not only is the height of the apple tree controlled by the root stock, but you can match the rootstock to your soil conditions so it grows to its fullest potential. For example, if the soil conditions are like many in this region with high amounts of clay soil that tends to hold water, the rootstock called MM111 needs to be the rootstock of choice. The tree's height would then be a semi-dwarf and you will get the first harvest of apples in about 3-4 years.
Now, if you use a rootstock like M7 which is also adapted to clay conditions, you can be awarded an apple harvest even earlier, say in 2-3 years.
As you can see, an apple tree isn't just an apple tree. You have to match the tree, especially its rootstock, with the soil conditions in your landscape. I would highly recommend you order apple trees from a nursery so you can be sure as to what you are getting. Have a good day.