How much room do you have? Is there an ideal mature size plant you want for that area of your yard?

Magnolias have comparatively shallow root systems, so you want to be able to plant it were you won't trample/compact the soil around/over the magnolia's roots by foot traffic, vehicle or mower wheels.

Magnolias make a huge mess in the Spring after they drop the flower petals and again in the fall when they drop the leaves.