Gotta go with the "groupthink" here - Saanens and Nubians are likely about as good as it gets when it comes to human/goat sexual interaction. Both are reasonably sized to make "lining things up" pretty easy, both are anatomically able to accept being penetrated to full depth by a (typical - certainly there will be exceptions) human penis without either side feeling any significant discomfort (or worse, suffering actual damage) and both of them are (usually) inclined toward at least being tolerant of, if not outright welcoming toward, being physically approached close enough that penetration is possible, rather than being disposed toward going straight into "OMG! The two-legger is getting closer than the width of the pen away! FREAK OUT AND FLEE!!!!" behavior like many other goat breeds seem to be.
Going the other way (human female penetrated by male goat) is likely to be a total disappointment for the woman. The goat will probably be just as happy, since he gets to bust a nut, even if what he's busting it in can't even tell he's penetrated it, but I can't see the woman getting much out of the experience. I say this for two reasons: First, I haven't met a goat yet, of ANY breed, with a penis all that much thicker than a pencil. Second, for goats, mating is, quite literally, over in seconds once the doe stands to be mounted. It's pretty much "follow the doe around bugging her until she finally stands still long enough to mount, hunt for the hole, and once found, give one or two thrusts to penetrate, then drop off, semen deposited, mating completed." It quite literally takes longer to type/read the description than an actual, complete-with-ejaculation-inside-the-doe mating takes. I can't imagine a scenario where it would be even remotely likely for a woman to get anything (beyond the fantasy) out of having a buck mate her - I suspect she'd have a hard time even being able to say for sure that she'd even been penetrated, let alone inseminated.
