I use the Mio Link and like it quite a bit. It seems to work great and it is small enough, unobtrusive; pairing with my Garmin was super easy. I think the Mio Fuse is a bit bigger but it has a display. The Link's light changes colors depending on what heart rate zone you are in...Fuse probably does something similar. I very much prefer the wrist HR monitor over the chest, which I always felt on rides. I forget I have the Link on most of the times.

The Mio Alpha2 is quite a bit bigger but does a bunch of stuff the Link doesn't do. Maybe worth checking on depending on what you are looking for. A brief look at the Mio Alpha2 optical heart rate watch | DC Rainmaker