My bets are:

• Kamiya
  Same as Shihwa but with a single-target 3rd skill. Only guaranteed stun on the target if crit and only guaranteed crit if asleep (not amazing). A new 9-tails skin is also coming out soon, and Com2Us stated that, if existent, the HoH bosses will show off the skin (so this might be the one they want to show it with).

• Bering
  Another Bomber without bombs. Instead of pure multi-hit wonder for NB10 as his brother Zibrolta, he has an AoE that Silences for 2 turns with 75% chance on 4-turn CD (maxed). Nice with Despair runes though.

• Ran
  Same first 2 skills as Su and Yen but with a 3rd skill that reduces ATB single-target by a possible total of 80% with a 52% chance (85% chance per hit). If the ATB is reduced to 0 it stuns. Meanwhile, Su stuns with 2 debuffs up, has a higher multiplier and higher Base Attack stat. ofcourse, she has no elemental weakness though.

• Icares
  The close-to-one-shot-monster from ToA, being an Attack type with a 1st skill 325% multiplier, 2nd skill AoE 230% Multiplier, then the last skill scaling of 30% HP (same as Arnold). What she has up from Arnold though is that she gains another turn if the enemy dies. Attack type to build tanky. The 2nd skill has a heal though, but only for 10% (it's the same as Acasis