Hypothetically, what is your preference?
It wasn't hypothetical in my case.
Perhaps I'm ignorant but is there some Christian proscription on marrying non-virgins?
Strictly speaking, no. But...
The admonition against being unequally yoked is often interpreted to mean, among other things, that Christians should only marry believers. Believers are expected to reserve sex for marriage. So there's that.
Obviously, the Christian bride or groom may have had some, uh, experience from before they believed. Or may have strayed after.
So, no, there's no real proscription.