I think the preference is subjective, like Cornflower Blue said, and it would depend on a few other factors as well:
- Your build (this cannot be simply determined by height, since your neck and shoulder muscles come into play)
- What size charm/pendant do you plan to use with the chain?
- What shape is the charm/pendant?
I am on the petite side (5'5", 105 lbs), but I played volleyball and am muscular around my neck, so there's no way a 16" chain would go as low as it does on Krysta (which looks lovely, by the way). For me a 16" chain sits right underneath the dent btwn my collarbones.
I do like that length (16") for petite pendants and own quite a few chains, and I think it works well for lots of their mini-sized charms (1" or less).
For bigger pendants, though, I think it would look kind of weird (on me anyway) w/ a 16" chain, as the charm/pendant would be sitting right on top of my chest bone. I recently inherited a blue agate cameo from my mom that is framed in 18K gold, which is about 1.5" in height. For that, I tried on different length chains at Tiffany and settled on an 18" open link gold chain. I like how it hangs lower on my chest. (Maybe a tad lower than Krysta's picture.)
I also tried on some of the key charms, and 2" and bigger ones looked strange on a 16" chain on me, because it's a substantial metal stick hanging right from the middle of my collarbones. But if it had been a round gemstone or more flexible pendant, I might have felt differently. So it all depends!
IMHO, you can go with 16" if you (or really your neck/shoulders) are on the thin side and are thinking of mini-sized charm; if the pendant is any bigger or if you are average (are we talking American?) size, 18" might look better. It's all up to you tho!
