The shape / size of a tree.

There are two aspects to the form of a tree, when considering which tree to plant (or where to transplant a tree to).

The first is the ultimate size of the tree, an arborist will automatically visualise the mature tree in the proposed location.  There are trees that even at maturity are small, others massive and all sizes in between.   

The second is the shape of the tree, it has to fit the space, there are wide spreading, columnar conical, weeping, rounded canopies ... trees.  

We do not want to plant trees that will require future management to control their ultimate size or shape. This is an unfair burden to place on future generations and if often detrimental to the tree.

When selecting trees, it is prudent to understand  the future size of the tree.  

Notwithstanding this you could take the approach of many Local Authorities and plant trees which if left to mature would be the wrong tree, but they are planted with a set time span, so they are replaced after 20-30 years. This is a pragmatic approach, especially in a risk adverse climate, not allowing them to get too large/having too much influence. Please note, this Local Authority approach is an informed expert assessment of each tree and each location.