I used Xytex but it was all done via my UK clinic so I’m not sure how difficult the actual process of ordering was- I just told them which donor I was interested in. It was pricey compared to the UK but I felt it was worth it.
I liked the wide choice of donors and especially that you could see photos of them (both from when they were children and as adults) and that there was so many personality details, as well as more genetic/health testing and info. I felt all that extra compared to the donors in the UK was something my DC might really appreciate when they are older and probably get curious about their origins.
Xytex even used to have a board/forum where you could potentially get in touch with your donor and others who have used your donor (so your donors “siblings” parents) like I was able to - I don’t think they still have it though 🥲. But I’ve noticed that in general using an international bank means people seem more likely to be open to early contact (which is apparently what donor conceived kids often want as they reach their teens and understand more about genetics). So you still might be more easily able to connect with other siblings parents or your donor via other donor forums/social media if your DC wants to/it’s something you are interested in.
As for quality, my clinic didn’t mention anything in particular and I didn’t ask- but anecdotally my first IVF round with a donor from a UK bank was unsuccessful, as was the previous IUI’s I’d had with that UK donor. I swapped to Xytex and 1 of my 4 embryos with that donor became my now 3 year old son. (The other embryos sadly failed, but as I was by that time age 40 when I made them, it was much more likely the age of my eggs than any issues with the donor - I even had a chemical pregnancy/early miscarriage a few months ago trying for a sibling with the remaining embryos, which while heartbreaking was still much further than all the BFN’s with the UK donor, so might be another indication of the Xytex donors quality).
My donor seems lovely and if he was still donating and if I was younger I’d have definitely done another full IVF round to try again for a sibling for my son. But as things stand, as well as online contact with the donor, my son has a dozen “siblings” around the world whose parents I am in contact with (and obviously there are likely far more out there who haven’t made contact yet) - so in terms of numbers of babies made, the sperm quality seems alright in that regard too 🤣.
Hth!