17s are good. They are generally less expensive and you can go with a higher profile tire which will help keep the rims from bending. There also doesn't seem to be a huge difference in size contrast between 17s and 18s when you look at pics. However, in real life, to me there is a difference when looking at the rims on cars and with a car the size of the legend I would rather have 18s. 18s just seem to fit better with a luxury car like the legend, 19s if you can afford it.
