I have my own "tier" list. Yes, a tier list for a RPG. This is in order of whom -I- think is useful, before all of the new abilities were added in. Note that this is subject to change now that all of the newer abilities are in (Weapon Bless, Souleater, Pray, etc.). "? Tier" are those that I don't know how they'll fare at all yet.


S: Remilia, Koishi
A: Marisa, Sanae
B: Cirno, Meiling, Yukari, Alice
C: Reimu, Reisen, Youmu, Mokou, Utsuho, Yuuka, Byakuren, Patchouli, Momiji
D: Sakuya, Aya, Komachi, Keine
E: Nitori, Suwako, Advent Cirno
?: Yumemi, Hope, Nue, Rinnosuke



Reasonings:


S Tier: Remilia is solely up here BECAUSE she is THE absolute strongest physical attacker in the game, beating out even Meiling. Top that off with some good Absorb and Shadow attacks. Koishi is mainly up here due to how versatile her moveset is right now, and some abilities (such as Flare and Freeze) are pretty powerful for the time you get her.


A Tier: Marisa is just all-around powerful, and even if she can't use magic against enemies, she still has other options (well, only really Stardust Reverie and Attack), so she's not COMPLETELY useless. And Steal is always good! Sanae...well, Sanae is pretty good both as an attacker and supporter (and she's one of the few characters with a Revive ability). Falling Stars is her highlight though.


B Tier: Yukari and Alice are both really solid characters, though Alice will ONLY reach here if her skills get upgraded a bit. Yukari is also up here due to her inherent Ribbon. Meiling is of course here due to her massive physical attacks as well as being a good healer, and Cirno well...Cirno is pretty versatile in what she can do (and all of her summons, bar Tewi, are AoE at that).


C Tier: A LOT of people fall into here, simply because well...this is basically the average characters. For instance, Yuuka is here mostly because she DOES have powerful moves, but she's slow and has a LIMITED selection of moves, and Reimu is here due to even though she has an extremely versatile moveset, they can only go so far compared to everyone else that deals better in those categories (i.e. Komachi for statuses, Marisa/Patchouli for Magic, etc).


D Tier: Characters that AREN'T terrible per say, but they're very limited in their capabilities and what they can do. Keine has the potential to reach S or A Rank, but only by getting ALL of her skills.


E Tier: The characters that nobody would use pre-Beta4 2.0. Nitori was all but useless due to her low MP and very limited moveset, Suwako was unreliable, and Advent Cirno requires her to upgrade her skills a LOT, as well as level her up a lot more compared to everyone else.



So that's how it is. Of course, others may have different views on this list, which of course I'd like to hear from them on it~