I prefer x264 since all my devices can play it, though x265 is great for file sizes.

I really love AV1, it's very small in file size and it's completely free, meaning that it should play anywhere were it was implemented

RealPlayer. I love how every video sounds like they're taking a shower.

For codecs it is highly dependent on the release group. For 4K it is the only valid option, but for 1080p a lot of groups make their x265 encodes too small and sacrifice quality. Take a look at the group rankings in the trash guides for sonarr and radarr for a general idea if who is the best/worst.

As for Tdarr, you should only really use it for audio and subtitle processing. For one you should not re-encode video so unless you're starting with remuxes you're further degrading video that is already degraded. And for two it's best left to the people who know what settings to tweak for each movie or episode. There is no universal setting that works well for everything so while you might be able to get acceptable quality with automation it's never going to be great. The best groups already took the time and effort to get it right so you might as well get those and save yourself the time/electricity.

HEVC 10 bit in order to reduce banding for animation, especially during dark scenes. I know H264 Hi10 exists, but it has poor hardware support, so using HEVC 10 bit is the best option (I don't own a single streaming device that supports HW accelerated Hi10, besides my PC). Also, an added benefit is reduced file size. I find that doing my own encodes is very rarely worth it, but when I do, I use FFmpeg in the CLI and not tdarr.

Can't get enough of x265. The size to quality ratio is very good and all my hardware supports it.

In this thread: people that think quality is based solely on the codec used.

FLAC, because you didn't specify what kind of Codec.

I mainly stick to x265 for the size. I'm not too snobby with quality and for the size its fine with me. I want to like AV1 but have issue with playback on some of my devices. Usually i just play locally off a HDD on xbox (Kodi) . This may not be an issue if/when I get a NAS. Not sure if there are issues with transcoding as I haven't really looked into it

VP9 for video and FLAC for audio. Avoid AV1 because my GPU can't decode AV1.

Never really thought about it. Just download whatever and Plex then transcodes it if necessary…

x264 or x265, depends on release and availability. If x265 looks better than x264 then it is x265 for me. In some instances I have caught x264 looking better, although not often.

I dont use Tdarr because of its lack of more complex rules, but I do use fileflows to re-encode old videos on my server based on some rules considering its overall filesize, current format, and which library it is in. If the flow decides the file should be encoded it is converted to h265 10bit at a high bitrate, if it somehow ends up bigger than the original it does it again with a higher reduction factor.

h265 vp9 av1 opus