Should we upgrade Mythic or Korthia gear?

Which gear should we prioritize wearing/upgrading over the other? I have pieces from both Mythic and Korthia (around the same level). Valor seems harder to acquire than research. What is the most optimal way to get into end game content?

Some of us have the opposite problem–valor is easy to acquire. I’m personally not very happy with the looting system for Korthia as its taking too long. I’ve been dailiying and campaigning every week since 9.1 launched and I still can’t put any of the really -well-statted items that I’ve gotten from the Korthia campaign PAST 220. (Crit/Vers is rare in SoD; but isn’t in mythic dungeons) but it seems to be on everything from Korthia.