What speaker is the most musical, one you never want to sell?

For me, the Falcon LS3/5a are my favorite. I have it and is my current reference speaker. I also like the ATC SCM 19a but sold it and got the 11 and still sounds nearly as good as the 19. 

But in my opinion, it is all room dependent.

for Floor standers, another speaker that left me an impression that I used to own was the Dunlavy SC-III.

My present Golden Ear Triton Refs.  I have owned them since I got them new in July 2017.  No desire to change, extremely satisfied with them.  If I ever won the lottery, I might look into the  Legacy Valors. 

I picked up a pair of Eminent Technologies LFT-8b speakers last summer on an impulse..they were close by and priced right..I figured I have nothing to lose. Talk about a home run. 

No doubt there will be other speakers in the distant future, but for right now..they do sooo many things right. I run them with a sub, but they do well all on their own. Absolute pleasure to listen to and respond well to upgrades up the chain. I have a number of other projects going on right now, but I expect they'll get upgraded to the 8c models this year sometime. A really inexpensive investment in a wonderfully performing speaker. I don't expect they'll ever be sold.  

My Volti Audio Razz and also have the Volti Lucera…will die with them…

My keepers are the Klipsch LaScala AL5's. They just seem so fill in my media space so perfectly.

I have two extra sets of Polk SDA SRS 1.2TL's that i just can't let go, thinking I'll build a full on home theater before I depart....but probably will go to my heirs to sell.