Yamaha MG06

After more than a year of using it, I'm rating it 4 and not 5 stars because it would have more features similarly to the competitors; the stereo channels, for instance, don't have eq. However, what it does, it does well. It is not totally silent but has a good sound quality overall.
The mic filters are good for what they're intended, but you can also use instruments in those channels. I use, for instance, a synthesizer in the mono channel with the filters on (otherwise it distorts the sound).
Using the mono channels for a bass guitar doesn't work very well; although you can get the sound, it somehow reduces the range of the bass' treble/bass knob.
The stereo channels work particularly well with synthesizers, returning a clean sound. I use it regularly with some combination of keyboards, including a Nord Stage and a Korg Opsix.