If xneelo registers my domain, who will the legal domain owner be?

You will be the Domain Name Holder.  Technically domains are never owned but are leased from a registry on an annual basis, giving the registrant legal right to the use of the domain.

We will be listed as the technical and billing contact, as we manage the name servers and domain renewal on your behalf. You will be listed as both the registrant and administrative contact (unless specified otherwise by yourself), therefore having the full legal right to the use of your domain name.