Tiers? There's no such thing for this game yet, and I don't think there will be for some time.
Filia just doesn't get a lot of use, probably because she's the "basic main character" in a game that's full of really interesting characters. Not that she isn't interesting herself, Skullgirls just sets that bar pretty high.
Filia's far from "low tier" anyway, though, which is why the creator of the game's engine, Mike Z, has been using a lot of solo Filia at tournaments to show her off. The way he talks about her it seems like he thinks she's one of the strongest in the game.
I admit, I voted for Parasoul in that feedback questionnaire with the first round of voting (due to that nice overhead swipe), but playing as Filia again... I like rushdowns.
