I really like the features of both units. The Zoom H5 is most useful because I can use it for field work as a research scientist, as a USB audio interface, has the connectivity for a DSLR camera, and it has a variety of accessories you can attach. The BOSS Micro BR has a lot of editing, mixing, effects, etc. features that come in handy as a guitarist... although I don't think I'll ever use it for mixing or effects.
From what I've been able to gather from reviews and demo videos, the Zoom H5 has a pretty damned good quality sound. One video compared it to a Scarlett Focusrite which I know to be a pretty good (not amazing) recording interface.