I would definitely go browband.
I have had one ears flung off horse's heads if they throw their head or even do a good shake while standing still.
I also rode with a lady not two months ago, with a one ear and a snaffle, and the horse flung his head, lost his bridle and took off running for home (she was on the ground holding him at the time).
I personally feel one ears only work okay with a curb bit. Because then when you pull back, it will give some poll pressure and tighten the bridle a bit. I have noticed with a one ear and a snaffle, if you pull back, you get a gap in the bridle at the horse's poll, which makes it really easy to fling off.
So I'm sure there are some one ear believers out there or they wouldn't be so popular, but as a trail rider, I strongly prefer browband headstalls.