the big one: how do you choose speakers? By what features, data?

@erik_squires exactly! I don't need a Ferrari (not that I can afford it) but I also only listen to short times so I want the punch...

Yes, a good speaker will be reasonably competent with all types of music.  But, depending on a speakers strengths and weaknesses, some kinds of music may be a bit favored or disfavored by a particular speaker.  For example, the Zu Audio speakers are extremely dynamic sounding with the ability to deliver extremely sharp-edged attack to the notes.  They sound very fast and lively with demanding electronic/dance music.  But, that comes with a rough, peaky sound (prominent upper midrange and high end) that might not be so objectionable for that kind of music, but it may be less loved playing acoustic music.  

Every speaker has its strengths and sometimes that strength is anathema to some other quality.  The only way to get around this is to have multiple systems (isn't that a dream?).

@larryi that makes sense, thanks! 

And no, I don't dream about multiple systems, just one :)

I use two criteria for speakers - My left ear and my right ear.  

In home trial is important, but it's hard to compare with other speakers. The sound in an acoustically treated store room will not be the sound in your room. I am a firm believer in controlled HF dispersion to prevent early reflections. I also believe there is no substitute for room treatments. The LEDE theory has always worked for me, Live End behind Dead End to the front. Don't go by specifications, nobody has an anechoic chamber for a room. Most important trust your ears in your room. An audio chain is only as strong as it's weakest link. Matching components is important and there are a lot of factory direct places that allow 30 day in home trials.