We have a Jabsco Quiet Flush freshwater electric head
. Works fine, haven't discovered any major flaws in the system or design, and it's reasonably quiet. Had to replace the pump/motor assembly at around the 10 year mark, not horribly expensive, relatively easy fix (since we have easy access).
There's a Raritan
unit that get's good reviews
; Elegance-something-or-other. No personal experience. There's also the Vacu-Flush system, which works well enough, too, and we had one of those in our previous boat. I found the big POP when flushing
the latter disconcerting, but it was otherwise quiet.
If I had to replace our current
QF, I'd replace it with another identical QF.