Not to guide anyone in one direction or another, but I feel that if next year seminar will be like it is this year, it is not the place to go if you are looking for a year to go higher (and not to fall). There is a group of good girls there (I am not denying that) but I would be hesitant recommending it to someone. On the other hand, the seminary all depends on that years girls, so next year it could be great. as far as new-yorkey, it is.
Ateres would be best described as an out of town bais yaakov seminary. There are tracks, so academically there shouldn’t be a problem whether you want honors or a easier level. They are very good about letting you learn on the level that is right for you. Yes, the stricter rules could get annoying at times, but it is for the students best. As far as strictness regarding missing classes, they give the students a very reasonable amount of personal/sick days so if you need to go somewhere during the school day you could without consequences.
Hatzlocha Raba on this hard decision, and everybody ends up where it is best for them so don’t worry too much!