The people at
Flirt4Free are one of the friendliest most helpful team I've come across. Each holiday season they send me a thank you card, with real hand signatures from a dozen of the team members. With that being said, I have no worries with changing whois details to their credentials and the domains are still under my control in my registrar account.
I have a few white labels with them and as far as I know straight, gay and transexuals are the whitelabel niches but there could be more that I'm not aware of. Check them out!