30. I use either, Specs is usually better though, because it handles all walls and all physical sweepers (& setup sweepers), scarf only handles walls (& setup sweepers) but has the advantage of boostinng your speed.
That, and Rotom can utilise specs better if he decides not to trick.
But really, both are fine, theres no completely superior one, its just dependant on your team.
theres always CB too