I use the Mirricyle mirror on my road bike - the one that mounts to STI shifters. On my touring bike I have an old Blackburn mirror. You can't buy that design anymore, alas, so I'm trying to protect mine as long as possible.

I have tried all sorts of mirrors, including the Take-a-Look. I've tried one that mounts on my bar end, eyeglasses, brake hood, and the Mirricyle. I've never like the eyeglass type - I think my head is too big. (?) The bar end was too far down to be convenient and didn't show enough. No mirror I've tried has been perfect. The Mirricyle loosens up due to vibration. I have to carry an Allen wrench for it. One time I tightened it too much and broke it, so I have to be carry. The Blackburn vibrated too much, so I added a wooden dowel brace. It's clunkky but it works.