About Cirno, her defensive stats aren't THAT awful, with some a lot of investment you can turn her into a tank. And that might even make some sense if the only thing you need from her is speed debuff or paralysis.
But, hey, Hina is a tank without much investment and can debuff not only speed, but every stat instead. :V
Well, Cirno does seem to have the fastest level up rate this time around(unless the rate for Chen is faster still, no one seems to of listed Chen's level up rate yet), so something tells me that you have to level her up more than most characters to get a similar level of stats from her.
Given that thought, it would seem like Cirno would be most suited to using the Transcendant subclass, as the boosts from that class would become more effective for her
because of her fast leveling up(if my guess about the boosts from Body Reinforcement are correct, then maxing out said skill with raise her HP, ATK, DEF, MAG, MND, and SPD growth rate by 3.0 per level, plus the 0.3 growth rate gained from just having the Transcendant subclass), turning her into, well...
Growth rates before Transcendant:
HP: 10.2
ATK: 9.8
DEF: 6.8
MAG: 9.8
MND: 5.4
SPD: 9.4
Growth rates after Transcendant:
HP: 13.5
ATK: 13.1
DEF: 10.1
MAG: 13.1
MND: 8.7
SPD: 12.7
And this is before you add her Speed Boost Skill or anything else to the mix with her rapid leveling. "Strongest Fairy" indeed.
As for Hina, all that's needed for her is to stick a Hexer subclass with Hexer's Conversion turned on, and her Biorhythm of the Misfortune God becomes a powerful means to restore all of her HP and MP, on top of her usual Misfortune Reversal buffing her up, making her into a very effective Mind tank.
Also, for the sake of actually being able to quote the technical stuff from the previous LoT2 thread(the stuff that isn't already on the wiki, at any rate), I'm posting this stuff here, from Validon98's post(and I'm forced to learn how to make a table from scratch, since I can't see the format of the code that was used to make the blasted thing, grumble grumble)...
Subclass Growth Rate Boosts
| HP | ATK | MAG | DEF | MND | SPD | MP | TP |
Guardian | 0.8 | - | - | 0.4 | 0.4 | - | - | 4 |
Monk | - | - | - | - | - | 0.6 | - | 6 |
Warrior | 0.6 | 0.4 | 0.4 | - | - | - | - | 4 |
Sorcerer | - | - | - | - | 0.4 | 0.4 | 2 | 2 |
Healer | - | - | - | - | 0.4 | - | 2 | - |
Enhancer | - | - | - | - | 0.4 | - | 2 | - |
Hexer | - | - | - | - | - | 0.4 | 3 | 3 |
Toxicologist | 0.4 | - | - | - | - | - | 2 | 4 |
Magician | - | - | - | - | 0.4 | 0.2 | 6 | - |
Pharmacologist | 0.8 | - | - | - | 0.4 | - | 2 | 4 |
Strategist | - | - | - | 0.4 | 0.4 | - | 2 | 4 |
Gambler | - | 0.4 | 0.4 | - | - | - | - | - |
Diva | 0.4 | - | - | - | - | 1.0 | - | 4 |
Transcendant | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | - | - |