I have wrist and ankle. I keep the wrist one with my helmet, and only wear it when I ride. I wear the ankle one much more often (and wear it when I ride, too!) because it's so much more comfortable and it isn't visible to every Tom, D*ck, and Harry who comes near me.

The ankle one also does a great job of holding a ChampionChip during triathlons!

I got my son an ankle one, and he seems to have lost it already.