What do you care about in this hobby?

Sound quality of course. Because I enjoy the technical side of this hobby as well, I almost want to split that category into sound quality and musicality. I am amazed at the technology that can deliver this level of performance in my home. Aesthetics matter to some degree, particularly with speakers. I also enjoy the endless possibilities, some day I may settle down with a system.

1. Sound quality.

9. Experimenting. 

10. Everything matters

First and foremost, the ability of the system to express the emotion of the composition and performance.  I have auditioned 7 figure systems that have accurate sound quality, but fail to express emotion and do not touch my soul, and other much less expensive systems that reproduce the composition and performance in a manner to bring a tear to my eye and fulfillment to my soul.  I recognize this is a very subjective quality but critical  IMHO.
 

The others are listed in order of importance:

• Sound quality, especially timbre. 
• High benefit/cost ratio
• Build quality and reliability 
• Excellent customer service/Dealer representation 

Design and parts quality are important but not a per se’ concern, for they are evident in the execution of the design intent during the design phase, design transfer, and manufacturing process,  and expressed  in the SQ, B/C ratio, and BQ and reliability listed above.  Measurements are of no concern other than electrical specifications for determining component compatibility.  

+1 @jsalerno277 Couldn’t have said it better.  The only important element I would like to add right behind SQ is:

- Discovering new music in a convenient easy manner.  

High quality streaming has really changed the game for me.  No more costly physical media to buy, store and discard . 

I've been into audio for decades and it all matters to me. It's a passion.