Serrah Keregan; the queen of blades (starcraft) :
[Kinglugia], [Alexander], [MHLord]
Elite commander Dostya; coordinator of the cybran(supreme commander):
[cross_grave]
Sir Integra Fairbrook Wingates Hellsing (Hellsing):
[Selias], [Xicree], [Undying Lich-King]
[X] Revan, The Revanchrist:
[Slayer Anderson]
[X]Princess Rhianna; priestess of the Aion(supreme commander):
[staplesdex2], [Bloodshifter], [Fellgar]
[X] Shokatsuryo Shuri - The Hawawa Strategist (Shin Koihime Muso)
[Adyen]
so, so far Keregan, Integra, and Rianna are in the lead.
I leave the voting open for a while longer until there is a clear winner, but if there isn't then I'll do them one at a time.
The Keregan route could be concidered easy mode. She was a battle psychic who could create nuclear level blasts from having a temper tantrum. Of the three she will give the greatest benefits and flexability to Usagi. She can act as both commander and frontline Heroic Unit. And [Undying Lich-King], Keregan would give Usagi the best combat skills due to infestation and battle data on Keregan. Unfortunately the swarm will not be greeted initially with any sort of positive response, therefore you will need to operate covert for the first while, not to mention the odd crackpot trying to subvert or otherwise steal your zerg.
The Rianna route would be medium mode. She deals more in intrigue, subverting human Assets and healing or otherwise performing miracles. This route is mainly focused on the support roles, from building up, to maintaining your powerbase to governing your territories. The ups for this route is that you will have a better army/control of army, unfortunately the trade off is Usagi's combat abilities are quite frankly utterly pathetic, even Mira and Shadowsun aren't as squishy, and they're pretty squishy.
Integra is quite frankly the hard or hardcore mode. While not one on my list, I have read Hellsing so I have a good enough idea of her. While she is mid-high level in combat ability, her base stats are human, though still better then Rianna route, slightly above if she transforms, which considering the traits she will get, will only be done when she is grasping for straws, for the most of it she will not get stronger then peak human while untransformed. In terms of leading her army there are few better, though several others who are better at keeping said army together. Her magic for this route would best be described as paladin, buffs and auras, she is fully capable of buffing herself and her allies while doing serious damage or restrictions to her enemies with auras. I won't sugarcoat this, her rolls, considering what she normal has to do, will be cutthroat, while you can turn bad rolls to your favour with Keregan and Rianna routes, in Integra route you loose men and resources at a minimum, too many bad thing in succession can kill you.
On a few other notes the omakes and roll table.
General Omakes will get you a reroll(no modification the first time, additional gets penalties) or flip result for mess ups or you can make them into bonus rolls.
Omakes that become canon will net you some very neat things, from upgrades to new powers, ala 'do you want evil fries with that?'
Roll table:
>100: You win twice. You are so awesome that you can write in extra effects.
>Any Doubles: such as 11,22,33, etc, You win~
>101+: Super Critically Successful, adds modifications to next roll
>91-98: Stupidly Successful
>81-90: Critically Successful
>71-80: Successful
>61-70: Moderately Successful
>41-60: Neutral
>26-40: Moderately bad
>12-25: Not So Good
>02-10: Terrible
>01: This is so terrible that IT JUST MIGHT WORK! (reroll)
>-01-: Critical failure... this goes so horribly wrong that you could loose an army
>00: Super Critical Failure... situation that is so FUBAR that dying is a very real possibility
Honestly if comes out as a tie between the three then I'll do Keregan first then Rianna and finish with Integra.