I mostly have 1/8s and some 1/7s, so I'm pretty comfortable with their size.
Height-wise they're noticeably shorter than standing 1/8s even. Which should be expected considering both are sitting.
Width-wise Juliana actually takes up a lot of space considering her hair leaves the already pretty wide base, although Selvaria fits perfectly fine on hers.
But yeah, I'd say they're closer to 1/8 than 1/7s. 1/8s that take up a lot of base space, anyway.
Here's an image comparing the three figures, though.