A few notes from my experience.
I have ripped my collection of 4000+ CDs to uncompressed FLAC (I still have all my CDs). I can't hear much if any difference between the original CD played through my PSA PerfectWave transport and PW MKII DAC vs. the FLAC. When I compare the same version on Qobuz I get the same result. They sound virtually identical to me. I'm playing Qobuz and my FLACs through my Asus ROG laptop hooked up to my DAC with USB. Couldn't be simpler.
If you have a significant number of HDCDs then you will need a player or DAC that can decode them. If you rip them with dB Poweramp it has the ability to decode them and make a 20 bit file that recovers the additional dynamic range. On a few titles I have compared my ripped FLAC with the disc itself using my Krell CD250 and I think the disc may sound a little bit better than the FLAC. One thing I can say for sure is that an HDCD sounds better played through an HDCD capable player vs. a Red Book player. I go out of my way to collect titles that have this format. Part of the reason I think HDCDs generally sound good is because the studio had to use Pacific Microsonics converters which were the best available at the time.
I haven't compared my SACDs to their hi res counterparts on Qobuz. One of these days I'll try a few to see how they stack up.