I played both.
Kensei is more complete and balanced IMO and addressing more on melee attack with 2H sword.
For Dragon prince/princess, sword is somehow not that important.
Some of the skills don't have Tier bonus. And a lot of strong DPS skills cannot build charge.
And the passive dragon's finish has some strange issue that it would sometimes proc itself again and again, unstoppable. (At lv15 85% chance to proc)
I can press 1, 2, 3 and see my toon still cast for 10 more seconds.
I would like to wait to see a more finished one later.
Both classes are fun.