It depends what you want. If you are in the Apple ecosystem, then AppleTV 4K is almost perfect. Audio passthrough was supposedly enabled in the latest TVOS, but needs developers to enable it at an app level, if it works, then I would buy a bunch more. Decent remote, remote available in every current iOS device by swiping down, Bluetooth streaming support, decent ‘night’ mode etc. and a Plex build that generally works well. The rumour mill has been active about new hardware due at some point, and eventually it will be right. Let’s hope they integrate ‘find my’ into the remotes next time round.
Roku…. The latest Plex UI is horrible, the limited app selection may be problematic for some with other needs, but it’s simple, and cheap (ish), and I often give them to older relatives because honestly, it’s idiot proof and I can provision them remotely. I haven’t bothered to even look at audio passthrough on this, I would be amazed if it did anything other than ARC/PCM via optical, but that’s not what it’s about.
FTV4K Max etc. are decent, but audio is a problem again if you want to pass it through, that leaves the cube which isn’t cheap, still has audio issues and the whole platform has future OS concerns with Amazon moving away from it’s android based offerings as well as app blacklisting.
Shield is just too long in the tooth at this point, the earlier versions are hampered with a poor remote, a genuine replacement is £45ish and the dash advertising without a different launcher is annoying.
I have never owned an android box I liked, including the shields. Can they be made less awful? Yes. But usually it involves Openelec. Hard no for me.
That leaves the elephant in the room, a device that most people ignore/write off for a variety of reasons, but oddly works perfectly and has a decent media remote available for it (if you can track down a genuine one). The Xbox One S. HDMI audio passthrough just works exactly as it should, the Plex build is actually decent, it’s fast, responsive and will direct play/stream the usual stuff, and it’s widely available/supported. Oh, and apparently it plays games.