Units Low Tier?

[Cut]

Hello there.

I am pretty new to that game. And i don't know much about units. My highest lvls are 40 and 28 (Br/Su)
I was using 2 Weapon Barriers and ''Rear / Fresh Aura'' for now, because it had the most S-Def.
I was making my way to get those hiei in Ep3, but i have found a whole set in 2 bonus quest.
And i got 4 legs. Are the only difference the attributes?
Also i have found a ''Vent Hexa'', if this is any good?
So can anyone tell me what to do with all of this?

Ty very much!

[Anduril]

So, the thing about units is trying to find a good set bonus and affixes (the stuff like Stamina III, Power II, etc.). The reason that people used to recommend the Hiei set from the Matterboard is that those have decentish affixes (Blow Resist III, Ability II, Stamina II, and Spirit II), and have a set bonus of +60 All ATK and 10PP, on top of each unit's hidden stats of HP + 40, PP + 5, Blow resistance + 3%, and Shooting resistance + 3% (for a grand total of +210 HP, +34 PP, +75 All ATK, +24% Blow Resist, +9% Shoot Resist, +10 All DEF, and +10 DEX).
However, if you did not start before the release of Ep.4, those Hiei units are not worth the effort since you will outclass them before you can reach them (though you can also buy them off the Player shops).
But since you do have a full Hiei set from the Bonus Quest, your best bet is to grind, affix, and use them since you want the set bonus, which you would not get from the random mix of pieces that you otherwise have. Additionally, you can keep using them for a while (until you really need to upgrade) if you craft them, though that does get rid of the hidden stats (the set bonus remains, however).

And for future questions, the Quick Question Thread is your friend.