Steel springs will make the ride stiffer all the time. Air bags can be mostly deflated so you don't know they're there if you aren't using them. The ability to adjust them is a big plus.
Somtimes a stiffer ride is better. The Tacomas are known for weak springs that wear out the bump stops. Adding a stiffer spring helps to not bottom out on every little bump and so softens the ride. Of course, adding springs with a lot of arch and little give will make the ride worse, but soft springs with a slight arch actually improve many Tacomas.
