First of all: welcome!
I've not used otonajp myself yet, but from what I saw in otona-Sekai shipping, they could easily take stuff out of the boxes, neatly flatten the boxes and then ship em like that, making it less obvious. Might be worth mailing them for?
As for the products, I can only point you to some reviews, as I tend to stick to NPG stuff. The Julia+ is one of the best ones I've had so far though, so ExE knows their stuff as well.
the reviews, in case you hadn't seen them yet:
http://infernalmonkey.com/2017/05/18/puni-ana-spdx/
https://blog.onahole.eu/reviews/onaholes/puni-ana-spdx
http://infernalmonkey.com/2016/05/26/pu ... 3d-review/
https://blog.onahole.eu/reviews/onahole ... alf-mature
The main thing I can see being an issue, is the cheaper onaholes just not doing it for you any more after stuff like the SPDX. You might also want to get some toy bags, as they make storing things safely so much easier:
https://www.otonajp.com/onahole-toy-bag-large
https://www.otonajp.com/onahole-toy-bag-extra-large
I'm hoping some more experienced ExE users can join in and help you out as well. I've gone through a few misbuys/mediocre products till I found what I liked, and if you can skip that step, it's always nicer.