Bach suites for solo cello-best Tidal or Qobuz recording?

I don’t know that "best" has a meaning in this case. There are various schools of performance, ranging from quite HIP (historically influenced performance) to romantic. What’s best? What you like! Part of the genius of this music is that it can be played in various ways and still sounds like the masterpiece it is.

That said, the sound on the Casals versions is bad enough that I don’t enjoy them.

I suggest you start with the 2000 performance on BIS by Torleif Thedeen. It has BIS’s usual excellent sound and a judicious -- but not boring -- performance.

For definitive performances is good sound, try Starker on RCA or Mercury. For really great HIP versions, try Bylsma on Sony or his student Wispelwey. ("Student" in the sense that Beethoven was Haydn’s student.) Wispelwey has a three versions, but he's a great cellist, so they all should be good. I'd be inclined to start with the latest one.

For well played performances in audiophile resonant sound, try Rosen on John Marks Records and Watkin on Resonus.

Have fun!

Yes, in these times I prefer familiar music, or at least music not too strident or challenging. I'm listening to less Shostakovich and other 20th century composers; more to Haydn, Mozart, Schubert, and Bach.

It is striking how much my taste for music has contracted, with all the external chaos.

I had a listen to Wispelwey version #3 from 2012. They are quite idiosyncratic performances. I think Starker would make a great foil to this.