Imho , it all depends on where you want the seam and the bulk to be and in this instance how the seams will line up with the seams in the quilt. All four will give you the visual effect you are looking for. I have done several BOM quilts that have used a variety of methods. My issue with the picket fence idea is that if there are a lot of them and since I am a bit OCD, I would spend hours on pinning that intersection to get the point perfect - lol!! So, I tend to use the flying goose method when I am on my own because I am comfortable with it, it eliminates some bulk in the seam allowance.and I get a good point. The combo unit would work well too.
Take some scraps and make one of each. Find one the way that looks good and works for you.