I'm using JRiver on Mac for the last couple of months, and I'm quite enjoying it. It's stable, it sounds great, it lets me really get on top of library management and multiple devices, and has excellent support for multi-device and multi-room scenarios.
The software is extremely deep and customizable. That's great, but it demands a learning curve up-front, and the will to keep learning as your needs change. So, you need to be the type of user who enjoys learning new software and doesn't mind some head-scratching and forum-diving. If that's not you, keep looking.
JRiver also demands some ongoing time from the user in terms of library management. That part becomes a lot faster though. I can ingest half a dozen new albums, make transcodes for devices, tag and organize, in just a few minutes. I listen to tunes while I do this and it's actually quite enjoyable - but it's still relatively slow compared to something iTunes.
The software isn't perfect, but it's very strong. My quibbles are minor, and I haven't found any significant problems or scenarios that can't be worked around. And most importantly: it's getting me more pleasure out of my music. My lossless collection is more under control, more organized, more accessible.