I tried finding a thread about this but didn't see one. I hope I'm not asking a repeat question!

I'm still pretty new to cycling, but am looking into getting some kind of mirrors. DH and I have noticed we have problems riding straight when we turn to look behind us-- What are some of the pros/cons of eyeglass/helmet mounted ones and the kind you attach to the bike? Do you prefer one or the other (or both??)?

Thanks!