Best bookshelf speaker?

Lots of good options you have so far.  As mentioned above, for sure add the Joseph Audio Pulsar2 to your list.

I have the KEF Reference 1 in my main system and they are amazing.  I have turned my preamp up to full volume and there is no distortion.  Very detailed but not "bright", they are easy to listen to and throw a huge soundstage and have great imaging.  I have (and love) Harbeth P3ESR, but they are not in the same league as the Ref 1.  No experience with the other speakers mentioned.

Look at the Ref 3A de Capos, clean, detailed easy to drive

If $$ not a concern, and sound quality rules, I’d cross Kanta and B&W 705 off the list. Listen to both the Kef and the Sopra and decide. They sound very different. I’d think the Anthem integrated would pair fine with either.  My choice would be Kef but you'll find just as many who'd prefer Focal - personal taste.  Gotta listen for yourself