What type of bike mirror do you like? Helmet, handlebar... attached to glasses?

I used to use the end-of-handlebar kind, and I'd like to try a helmet type this time around. But I hesitate to glue anything onto my helmet. Do the clamp-ons stay on?

Thanks in advance.
Amy
p.s. I've had the flu for 5 days, so y'all are providing some nice entertainment the few moments I'm at the computer. So much time, so little energy. Good thing there's lots of women's sports on the tube this weekend. Who knew college softball could be engaging?