Vaccinations, hands down. According to my neighbor, my first two ped's, my cousins, my MIL, and so forth, I'm endangering the world starting with my children. My question to them is, if vax work, why is my kid a danger to anyone else's? But that seems to make no sense to anyone. My DH is on board, most of the time, but the constant barrage does get him down at times.
I have one cousin-in-law on the boat with me, and she (poor thing) has suffered this much worse than I, with many harrassing phone calls from her SIL's and MIL. (Her SIL even blamed her for her kids catching chicken pox, which they never even had!).
I have mentioned wanting to homeschool my 4 y/o to many (when asked the fave question, "So he'll be starting K next year") and haven't gotton any negative response yet, hopefully that won't be another social battle for a few years at least!
We have one Circ'd son and one intact (I wish I could undo what we did over a million times) and I have received ?'s about the difference, but the only neg thing ever said was once someone said that it just "looked weird". Of course it does, if all you have seen is mutilated ones! When answering the questions honestly with our (my) reasons not to, they all seemed to have really receptive ears to the cause so far. I wish my DH was as sympathetic, he is my greatest antagonist to that, but that is another novel.