Black Series Stormtrooper Helmet (Rogue One).
Has a voice changer. Could do without it, it's quite bad.
I like the shape of the rogue one helmet a lot more than most others - along with the fact that the vents on the sides (upper and lower) are actual vents (grooves) instead of just a sticker most helmets have (along with actual screen ones).
No ridge/gap around the mouth and the feel and especially the overall shape is much better than a lot more expensive helmet out there.
Black Series Darth Vader Helmet
Comes a part in three pieces with the important breathing sound.