I am so surprised the no one has mentioned my most despised block, flying geese. Yup, tried all the different methods and none work for me. I made one quilt that was all FG only because it was a labor of love. I don't love many others enough to go that way again.
I have quilting buddies that whip those little blocks out perfectly in no time flat, but mine are always crooked and seldom fly in good geese formation.
It is interesting what blocks cause us to stumble or at least pause. I love square in a square and bias binding is easy peasy and I can spin points in my sleep, I haven't tried curves because I am scared. That is silly, I know. I leaned to put in smooth fitted sleeves in a garment when I was a teenager, why not a curve in a quilt block?
This all is a quick indication that we are unique individuals.