There have been a few updates and additions to the library, so there is enough content there for me to put my take on things.
I'll go through each book, and try to highlight groups of monsters per book. For now I will omit Superheroes, Families, & Exclusive because they are more incomplete than complete.
-If i forget to mention a monster, just remind me and I'll look over it to see if he indeed was omitted/misplaced
-Yes, some monsters do overlap in categories.
-Categorization is based off 130 v 130 combat, less relevant to 100v100 combat where fights are shorter(less HP scaling)
Most value(appears in other books) and is a decent choice in those other books, generally a balance between an economical choice and a powerhouse.
example: G Nishant is in wings and evil legion but i wouldn't consider him to be high value because of his niche role as a defender and is somewhat outclassed in evil legion
Powerhouse: (a dominant monster) I would consider these the top picks of that book. They are usually a strong/counter to other monsters of that book, they have good synergy with popular monsters of other books, and/or an exceptional defender in that book.
Economical (breedable, teamshop) pretty straight forward, good option for f2p/small spenders and are relativity easy to get but are still very much an effective choice in wars. They are by no means weak, but generally less flexible in their roles.
-Most Value: Greedy Dragon
-Powerhouse: Greedy dragon, Frostwrath, Learnean
**Notes: Learnean is such a terrifying defender that his defensive prowess alone is enough to make me consider him a powerhouse of dragon.
-Most Value: Urias pet, Uriel, Scryb, Noctum, Goldfield
-Powerhouse: Uru, Tempest, G Uria
-Economical: G Uria/pet, GoldField
**Notes: A pretty weak book in my opinion, G Uria is a solid defender, while Uru & tempest are strong in their own right, they are a bit outclassed comparatively to the denial of other books. Despite being a breedable Goldfield is exceptional in this book due to his stun immunity.
-Most Value: Greedy dragon, Uriel,
-Powerhouse: G Ingvar, Caillech, Greedy Dragon
-Economical: Greedy, Ingvar, G Nishant, Arch Knight, Darkzgul
**Notes: Aside from G thetys, Ignvar is the only other general rated as a powerhouse in a book because of his flexibility and durability both as a defender and support on offense. Caillech eats greedy dragons.
-Most Value: Will Razor, Nautilus**, G Thetys, Sphyrunus
-Powerhouse: Nautilus, Cavenfish, G Thetys, Famperium, Blob, Hydratila(all)
**Notes: Until SP fixes Nautilus, he will continue to impact wars despite being an epic. Famperium and Blob are the few Sea attackers than are a major threat to the book. Blob is a strong pick vs the popular thetys, a minor drain is enough to stop her from using stamina devours.
-Most Value: Greedy Dragon, Demise
-Powerhouse: Kaih, Ouros, Barbatos, Demise, Metalhead
-Economical: Nishant's pet
**Notes: The second strongest book, next to female(due to zyla). Also the only thing keeping Ouros in check is Barbatos, yes you can possess him with Metalhead, but he just going to self buff or hit his allies for a paltry amount.
-Most Value: Nautilus
-Economical: Exo Skeel, Master Skeel, G Holter, Ultrabot
**Notes: At a glance it seems like a weak book, flips to the last page, ahh it makes sense now, timerion is carrying it. Though he is more of a force of nature in rarity wars(c,uc, r and e), Timmy's effectiveness does diminish a little in Legends v Legends, but in the right hands a Timmy offense rarely loses.
-Most Value: Zyla, Demise, G Thetys, Mommy,
-Powerhouse: Demise, Zyla, Shallinar, Thetys
-Economical: Thetys, Shannara
**Say hello the to the most busted book. From what I've seen anything + female book usually turns into an offense favored war, defenses can do little with so much available firepower on offense.
-Most Value: Will Razor Face, Noctum, Scryb, Harusami
-Powerhouse: Akhenotep, Nox, Harusami, Will Razor, Baba Yaga, Ra'zhul
**The strongest monster in UD are either stun immune or possession immune. Akhenotep's blind,daze, dmg reduction skill bypasses those immunities. Though the book is infested with dark, Baba Yaga's skill set & stats are too good to ignore.
-Most Value: Uria's Pet
-Powerhouse: Osur, Brontes, White Pandalf, Laomu, Alces' pet**
-Economical: Laomu, Alce's pet, Uria's pet, atum's pet, Arch Knight, Shannara
**Notes: Alce's pet can take over a war given the right restrictions. Brontes is an excellent/popular monster but can be a liability on defense due to the availability of Pandalf & Laomu.
-Most Value: Harusami, Zyla
-Powerhouse: Zyla, Krampus, Kaih**
-Economical: Goldfield, G Holter, G nishant, Nishant pet
**Notes: Kaih is considered a powerhouse to me because if a defending Kaih lands and sticks ignite on an attacking zyla, that is a kill. If the restrictions of a war ends up to be light on denial options, Krampus can take over on both sides of a war with his obnoxious speed.
-Most Value: G Thetys, Uria's Pet, G Ingvar
-Powerhouse: G Thetys, Atum, Ingvar