A sound answer should discuss, at minimum, three of the points mentioned below, supported by a case example where appropriate.
Certainty - a judge ultimately has to reach a decision in a case, and lawyers can advice their clients on the state of the current law and how it is likely to affect the case.
Flexibility - appreciation that judges are used to adapting the law to new or slightly different situations despite precedent.
Precedent decisions (particularly those of the appeal courts) - they provide detailed rules for later cases to follow as similar cases with similar points of law should be decided in the same way, following the ratio decidendi.
Judges (particularly those of the higher courts such as the supreme court) - carry great authority and their decisions are respected as being impartial.
The benefit to new / inexperienced judges in lower courts to be able to rely on the reasoning from the judegments of more senior judges higher up in the court hierarchy.