There are gurus that encourage that you chant ‘Om Namah Shivaya’, or ‘Hare Krishna’, or ‘Ram’, or ‘Praise the Lord’; and then there are gurus that do not discourage you to chant ‘Jai Guru Dev’, rather, they revel in it.
If you are wondering or may be confused about which one to follow, then bow down and accept the blessings of the former one; the one that encourages you to chant ‘Om Namah Shivaya’…
For it is she/he who may lead you to God, the Universe, or the Truth. The latter will just lead you to yet another ego-centric entity.
That said, keep in mind that God is within you, and so is the Guru. Look for the light within and let it lead you.
Om Namah Shivaya !!