I am currently designing a new scarf pattern and am contemplating the best way to begin. I am deciding weather to use Foundation Half Double Crochet, or Chain & Half Double Crochet. Foundation Half Double Crochet is widely popular, for obvious reasons: it combines two steps in one and you don't have to work into a fiddly chain. I did a poll on Instagram asking which method do people prefer, and the majority said Foundation Half Double Crochet. Although that helped me to make my decision about which method I should use in the pattern, I am still torn myself as to which method I like to use most. I don't think anyone really likes to count hundreds of chains or to work into the ridge on the underside of a long chain, but there are some times that I feel that chain and half double crochet are the way to go. Especially when I am working with finer yarns, because I find it more difficult to keep an even tension with Foundation Half Double Crochet. I also find it easiest to begin working into the back loop of the chain. My favorite time to use Foundation Half Double Crochet is with heavier weight yarns.
The pattern I am working on uses a double knitting yarn, but I will go with the public opinion of Foundation Half Double Crochet, but possibly include instructions for both methods, so everyone will be happy!