Why not HEVC 10bit? We’re quickly approaching the age of AV1 and HEVC has been on the scene for a decade now so might as well have a relatively recent codec and HEVC offers improvements of 20% bitrate reduction for same quality even for 480p content vs 264. Modern devices don’t have any issues decoding it either even in software and open source encoders are mature enough. AV1 might be an even better bet but encoding time takes a really noticeable hit compared to HEVC and client device support still isn’t entirely there, the encoders are also still a little more finicky than HEVC.

As to ripping DVDs to EAC3, I wouldn’t.

Almost all DVDs are natively AC3 regular dolby digital. You can’t add more quality by doing lossy conversions and the bitrates typically present for DVDs are low enough that doing a conversion to lower the bitrate doesn’t really make sense. We’re talking 512-640kbps for 5.1 audio (and 192 to 240 for stereo) which isn’t unreasonable and the damage incurred in conversion to save say half that IMO just doesn’t make sense with modern storage prices and the amount of storage being used for 480p content. You can easily save as much without damaging the audio by choosing HEVC10 as your video encoder. If you insist on doing a conversion for DVD audio I would suggest doing so to either AAC if you have a good encoder and know how to use it or Opus but I wouldn’t recommend it (all TVs pretty much natively play/decode AC3 audio so given you’re not saving that many bits you’re just inducing degradation of conversion from AC3 to AAC/Opus and again back to AC3 for playback).

Now for BluRays I fully agree converting from those massive 2000-4000kbps DTS-HD MA, TrueHD, PCM audio streams to EAC3 at 640kbps for multi-channel audio can save a fair amount of space at scale and doesn’t incur meaningful audio degradation (while offering equivalent quality to 1000kbps AC3).