I have the Sprintech on most of my bikes and am pretty happy with them. My lady friend gave me a CycleAware, which is the same idea as the Sprintech mirrors. I 'hate' that thing. The quality is a lot less than the Sprintech mirrors. The convex mirror is not smooth, with a little ripple near the edge. Distorts the fov. It also needs constant adjustment. Any little expansion crack in the asphalt knocks it out of position. Simple enough to reposition, but it's a pain to have to be constantly aware that it probably won't be in position when needed. The Sprintech mirrors are a bit more expensive, but they don't get knocked out of position by any little rough patch you go over and the mirror is smooth. (I'm stuck with the CycleAware mirror because I can't say to my lady friend that she gave me a piece of junk and I don't want to use it. Yeah, yeah! I know. I'm a wimp. I just don't want to hurt her feelings.) I purchased my Sprintech mirrors from Amazon.
Tried a helmet mounted mirror once, and just couldn't get used to it. My eyes are bad enough that I couldn't get the hang of quickly changing my depth-of-field from looking at my surroundings, then refocusing on a little piece of mirror a few inches away from my eyes. That mirror sits in its package. I really should donate it as a prize for some type of cycling fund raiser. I'll never use it.