The Fire TV Stick 4K looks like one of the better deals and one of the few streamers that supports DolbyVision, HDR10+ and HLG HDR formats. I just wish they'd throw in the Ethernet adapter.
The Roku Ultra is a little behind on HDR and as comfortablynumb likes to point out, it can't do MPEG2 (something that perhaps only those with network-based DTV tuners need be concerned with).
The Apple TV is stupid expensive for the limited support that it offers (though its the best solution if you're an iTunes fan).
The nVIDIA Shield TV is now more reasonably priced but I wonder if it can keep up with some of the newest technologies as it has been around for a while now.