Hi! I personally believe that many of the community who responded here has definitely got the right idea. Both are really relative, since Purification is based on a % of the base value, Refinement is usually recommended as well. I would look at the two as working hand in hand, as it is more recommended to upgrade them as you continue your journey in Naruto Online.

There are multiple guides out there, but the general idea is to ALWAYS make use of rebate events. What that means is to make sure there is a refinement rebate before doing refinements. Also, one should take into account wish credits and see what works best for you and if it is better to hold off on refining until you get more materials to get to a higher refinement. Sometimes it is better to save your refinements and wait for the best time to use them.

My recommendation (based on what works for me) is to save purifications before using them. Save around 200-300 Purification Runes and aim for a stat you want. Most players would recommend going for the gold initiative stat, this means foregoing the other stats and only aiming for the gold initiative stats and worry about the rest later. There are multiple different ways and stats you could choose, in the end it will depend on what you are comfortable with and works best for you =p

~Jib