I wrote an article for positive-feedback.com titled "Universal Disk Players Placed on Endangered Species List"
https://positive-feedback.com/audio-discourse/universal-disk-players/ about the demise of OPPO's sorely missed universal players. I included a list "2018 production Universal Disk Players" with eleven models and their capabilities summaries that readers of AudioCircle or Positive Feedback might consider. My list does not include the HDMI only entry level models from Samsung and LG that apparently only exist to help sell 4K UHDTVs.
As WC writes much will depend on how and for what the player is intended. Considerations include:
Do you want multi-channel analog audio outputs? Too bad OPPO was the only game in town for that feature. Not-OPPO players are 2 channel analog outputs on RCA and occasionally XLR. Be aware some players have no analog outputs and feed both audio and video to HDMI.
On the video side do you want to be able to play 4k UHD disks or just HD BD (Blu-ray)? Note current production ‘universal’ players include three video flavors:
1. True 4k UHD BD,
2. 4k up-sample from HD BD
3. HD BD at pre-4k video resolutions.
Navigating all the audio, video, and streaming options available is a big bowl of acronyms alphabet soup. I suggest asking what capabilities are must have and nice to have then study the models’ spec sheets.
I recently used the Sony UBP-X1000ES (4K Ultra HD Blu-ray Player. HDMI, USB, Ethernet, and S/PDIF. Analog out RCA. $549) in a 4k Home Theater upgrade. Nice player with good streaming capabilities emphasizing 4k UHD video from both the disk and streaming. Sound excellent via HDMI to Anthem MRX 720 Multi Channel Receiver. Picture to Sony VPL-VW285ES 4K UHD Projector is stunning. Alas, build quality no where near OPPO's.
For a more audio HiFi centric player one that looks good on paper (i.e. I have not seen or heard it yet) is the Yamaha BD-A1060 Aventage 4K UHD Universal Blu-Ray Player. HDMI, USB, Ethernet, and S/PDIF. Analog out RCA & XLR. $499.