Best digital format (non streaming)

Glad to hear that CD resolution still 'cuts it', since I am NOT and likely won't be for a long time a 'streamer'. And also came to find out that some 'remixes' (likely with much better resolution) and therefore 'better' are just not the same as the one made available to the public (for example on the original CD). 

Once you start listening to higher res recordings- And, I might add, recordings that were recorded at high res-you will hear the difference over Redbook.

My caveat refers to old recordings that have been resampled.

B

Now that I've heard SACDs played with their DSD resolution, I would rank the media as follows:

SACD

DVD or Blu-Ray

HDCD

CD

This is based on playing them all through the same transport and DAC.  So, basically, the higher the resolution, the better the sound if you're listening to the same recording.  Before I heard SACDs in DSD, I wasn't impressed with SACDs that were converted to 24/192 PCM.

The difference I hear is that higher-res sounds more analog--smoother with less digital glare or shrillness. 

Now, there are some CDs that were very well-recorded that can sound comparable to higher-res media of other recordings, but they are in the minority, in my experience--mostly audiophile labels like Chesky, Bainbridge, Telarc.

When you have a poor recording , there is only so much you can do, CD or High Res. But if you have a good recording, High Res can sound amazing! Also, a lot has to do with your setup. That Boombox from the Seventies isn’t going to be able to reproduce the dynamic range. But a good Transport, DAC, Amplifier and speakers in a well setup room, no that’s another story.

Assuming context of a high-quality studio master.

It depends on genres of music you are listening to.

For "simple" music, e.g. "a girl and an acoustic guitar", majority of pop songs, 16/44.1 CD format is more than sufficient.

To cover "complex", e.g. prog rock, classical, PCM 24/192 or DSD128 would be better.

For "extreme", such as symphonies requiring 120+ players, PCM 32/384 or DSD256 may be called for.

For storage efficiency, losslessly compress with FLAC or ALAC.