Do you want costume sets or costume pieces?
I do like sets when they help give a coherent look to a costume. I often will use the boots and gloves from one set, and the chest and legs from another. I don't have as much use for sets where most of the pieces don't seem to work outside the set, and seem like they're just there to fill out space and let you make Set Theme Guy with all new pieces. And overall, I'd rather just concentrate on the inspired pieces, and being more complete with those. For instance, if the Barbarian rings and belts had come out for both genders, and maybe some basic fur-lined boots and gloves, that'd have been enough. There are already barbarian-style hats, and I think it's limiting to feel that every pack needs to have a piece for every location. The strength of the costume editor is mixing and matching, not using preselected sets, in my opinion.
It might be useful to do occasional packs of really specialized but unrelated stuff, so that there's a way to put out things people are asking for without having to hype it as a complete set. As an example, maybe the Gunslinger thing could have worked as just a couple of pieces as part of a grab bag pack with friendly a la carte pricing. Not all packs need to be the same size and price.
Angel Witch II - Chord of Souls - Storm Witch II - Princess of the Dawn - Standing Horse - Witch of Xymox
Silent Scream - Shadow Witch II - Liquid Serenade - Nebulous Dawn - Ghost Witch II -Xiberia
Both. I don't want them to hold back on a costume *piece* that's good just because they don't have the rest of a *set* to go with it.
As for the rest, it's all "Varying degrees depending on what I want." Some sets are more difficult to make look good with anything but themselves (some, in part, due to tinting.) Others are far more flexible.
Wanted: Origin centric story arcs.
If you've only played an AT once (one set combo) and "hate" it - don't give up. Roll a different combo. It may just be those sets not clicking for you.