RinoZ
The Queen will never accept it and thwack any ant even thinking of suggesting it. Leeroy would be a decent choice but her importance in the war doesn't warrant giving her such a high level piece of equipment. Sarah would also benefit from it but she is fundamentally not of the colony (and may be strong enough as she is). That leaves Anthony but he already has a strong defense, though not as strong as a Legion armour. Besides, he is nearing his next evolution, which will once again make him larger and would require to reforge the armour pretty soon. Plus it would be a waste for the armour to drain him of his mana, given he is now more of the magic type than the physical one. My bet is actually on Tiny. He needs it most and would basically be unstoppable by anyone other than Titus himself. And that would let Invidia free to go on the offensive as well.
I think the armor would be given to Anthony, because Anthony always go to the frontline, although in terms of importance the queen might be more important than all, but ngl she's not that much in need of the armor since they would rather keep her inside the nest instead of fighting outside, unlike the eldest where they, instead of trying to keep him inside the nest, they gave him bodyguards. As for leeroy, lee roy is not that much important for the colony.
Honestly I see only three possible candidates for the makeshift armor: 1. Tiny (it really complements his destructive tendencies and will provide The Colony with a strong presence on the Legion front) 2. Leeroy (this would make sure that she doesn't end up dying and ensure that the Council doesn't lose a member) 3. Anthony (for obvious reasons The Colony doesn't want to lose Eldest so they would probably do anything to keep him alive) My money is on Tiny, but Author-san has surprised me many times so I'm looking forward to seeing how this plays out **: another option would be to dress the new antmancers with Legion armor, as long as it takes mana from the environment, rather than from them, they will probably be able to dive deeper in the dungeon without suffering from Mana Sickness; if this happens then they can be used on the frontlines.
...So...I just had a thought, a very delayed thought, bit a thought. Anthony's species os losted as being a Juvenile Paragon Ant...He started out as being a Juvenile ant originally and picked a strata of society after, too. So the question is, can Anthony pick a new strata as a Paragon ant? Like a Queen, for example? Not that he'd choose that even given the option.