Re: (Nutaku) Milenium War Aigis (English Version)
She's more important/useful than Olivie/Farne/Despara right? (considering that I have Sybilla/Mikoto maxed and Adele/Belinda/Yuyu near max).
Matsuri is mostly used for her passive buff while relying on lower cost advance guard tacticians (Uzume >>> Helena; or recently added Leora for afk setups) on the field. Most of the time Matsuri is placed only later on as a melee ranged support with her SAW. That's also the reason why most people chose Brave Warrior (20 % 1.9x damage) instead of Great Military Strategist (-3 cost) as her 2AW.
Farne is considered to be one of the worst black units.
Despara is quite good, but you have more than enough witches and Mikoto. She is noticeably better than any of your witches, but nothing you will need at any cost in the close future.
Olivie is great, because of her skill. Can't negate magic damage, but other than that she is a healable Karma. Her SAW with twice the attack speed is great as well.
Therefore I'd say for you it's probably indeed:
Matsuri (solely for the passive buff) > Olivie (as I guess you have black Karma) > Despara (since you already have lots of leveled witches and Mikoto) >>> Farne (because Farne)
Also, are Cornelia, Sue, Agnes, Uzume, Sabinne, Daisy and Flamel good units to train asap?
Moste noteable: Cornelia is considered OP bracket, since she is the best tank in the game. Only after SAW though, so it can wait.
Uzume is considered SS platinum rank: A definite first deploy, best support due to her AW ability and her skill. Level her asap.
Sue, Flamel and Sabinne are rather good (in decreasing order) and depending on what other compareable units you have may be worth leveling.
You can ignore Agnes and Daisy.