This is a real cliffhanger, because I'm really not sure what she'll pick. Going to the Tower of Books seems like the obvious answer because it was her original goal and represents Coco's inquisitiveness and willingness to push boundaries, but on the other hand, going back to the Assembly shows Coco accepting Qifrey's message and deciding to solve her problems herself rather than looking for a solution. If I had to guess, I'd say Assembly, if only because it defeats the point of Qifrey's speech if she doesn't. It really could go either way, though.