My first suggestion is a Blu-Ray player. The Sony players I have were under $100 and play MKV natively. This allows you to select different audio channels as well as captions. Depending on the file, HD audio can also be available. I have some ripped Blu-Ray discs with both DTS Master Audio and Dolby TrueHD audio that will play. And of course, you can always just pop a disc in to watch as well!
When it comes to media players, one question you have to ask is what will they stream? They all do Netflix, but not all do Amazon Instant Video. Also be careful, because not all media players stream from DLNA, which is what you need for Serviio to work.
The Roku players now support DLNA, using the free Roku Media Player channel (app). However, it will not stream HD audio, and it has limited media support, which means most of your videos will likely need transcoding. While they support MKV files, they will NOT play videos with a MPEG2 video stream. That is what every DVD contains, so a ripped DVD will always need transcoding. I've also never been able to get captions to work with the Roku, but haven't put much effort into it yet.
My daughter just bought an Amazon Fire TV. Outstanding user interface, but again does not support DLNA out of the box. I did discover an app yesterday that shows their Serviio machine, but we are going to have to build a profile for it, because it doesn't show any videos, which means it won't play anything without transcoding.

Dan
LG NANO85 4K TV, Samsung JU7100 4K TV, Sony BDP-S3500, Sharp 4K Roku TV, Insignia Roku TV, Roku Ultra, Premiere and Stick, Nvidia Shield, Yamaha RX-V583 AVR.
Primary server: AMD Ryzen 5 5600GT, 32 gig ram, Windows 11 Pro, 22 TB hard drive space | Test server: Intel i5-6400, 16 gig ram, Windows 10 Pro
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