For me 1-2 because it was harder for my then only child to suddenly have a sibling that needed moms attention. It went from me and her all the time to me and her and baby who needs mom a lot. By baby 3 both kids were used to siblings and my oldest was there to help the middle through and let them know it will be ok and new.siblings are great.

Neither, 3 to 4 was difficult. The others were easy.

Following. I’m due with my 3rd in December, going from 1-2 was a little difficult but overall a lot easier than I expected it to be. I’m hoping 2-3 will be easy as well but I always hear it’s hard 😅