There are many different types of steel to choose.  Generally stock steel is very good. Some aggressive turners and leaners like the taller steel like LS3, LS 4&5 and TYDAN and STEP. However going from shorter steel to the taller steel can be awkward, especially for STEP which has huge amount of metal on the toe and heels. These require quite a bit of getting use to time. LS3, 4 and 5  also require some break-in if changing from LS2. On the other hand, TYDANs are unique, they are taller like those other runners but they tone down the amount of steel on the ends so they generally feel great first time you skate on them.

Most skaters do not need the taller steel, regular height runners work fine for them.