identify a digital file format (and file /folder naming scheme) that is compatible with your endpoints / media server eg. phone, smart tv, roku, laptop, console , etc eg Codec and Profile and container eg AVC h264 4.1. MKV..and also same for audio.
decide whether you need the optical media strucutre/fluff in the digital library eg. navigating the dvd extras etc as a dvd - if you do this this seriously curtail your options.
if your going to use a media server to play content, then test the chosen rip specification thoroughly on all endpoints before ripping all your content to it (video, audio, multiple audio streams, multiple subtitle streams, internal subtitles in eg mkv or external subtitles eg stand alone srt).
hard disk space is not expensive but 1:1 is more unwieldy usually due to size/client compatability.
That said if you invested in space to have 1:1 isos of all disks, and then encode the iso in a second stage....you would be able to rerip more easily when standards/end points changed.
AVC/h264/4.1 is probably a good starting point for widest compatibility (supported by some transocding by media server, good compression)
if i was investing/investigating now, i would be testing HEVC/h265 as the expected successor.
Maybe a bit more transcoding in the short term, but long term an expected superior codec.
You will want the maximum amount of cores/ghz you can get your hands on as reencoding is highly threaded as is transcoding during playback.
with a well specced ripping pc
ripping dvds to iso will be limited by the number of optical drives and the performance of the storage subsystem, i suspect 1 optical drive per core, and 50MB/s disk performance per optical drive (2-3 per sata mechanical disk). Probably want multiple temp drives for ripping performance, and a raid 5+ array for end storage.
encoding ISOs to AVC/HEVC will be cpu bound, cant have enough cpus, all will be fully utilised... Investigate using GPUs/cuda to accelerate encoding, from little investigation ive done, ive concluded its not there yet in terms of quality.