I prefer acrylic stems because 1) I tend to chew the shit out of vulcanite stems (in fact, I use softy bits to protect stems, not so much for my own comfort), and 2) because of #1, I don't have to invest in taking care of a vulcanite but to prevent oxidation. That being said, from a pure aesthetic standpoint, I think well cared for vulcanite bits are a lot classier and I'm sure they're more comfortable to clench than acrylic.