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

Magic is what I listen for. If you don't hear something that moves you, move on!

I am cheap so I buy everything used. Almost. I did buy a streamer new. Got a deal though. Speakers take time to burn in. Some people sell them before they even know what the have. Are you patient? Join an audio club. Members unload good gear cheaper to other members. Tune in to the weekly zoom meeting and learn.

There are a lot of good speakers. Some will mate better than others with your amp.

Join the SFAF Club. $35/year. Best audio money you can spend. Friday 5pm Pacific is the weekly Happy Hour Zoom. 

@jeffseight 

The problem is I need to narrow down my list before I choose what I listen to.

SF is a bit far, I should look for a local club :)

The old real estate saw "Location,location location" applies to speakers but modify it to "Listen listen listen"

Ad copy and enthusiastic dealers can make you believe that brand X is the best thing since Rod Stewart sang standards at your dinner table. 

For me going out and doing the hard work of auditioning at the store and then at home with my gear in my room with my source makes some surprising conclusions. When you get to the "affordable" 10K speaker range they are all really good furniture, but they don't sound anything alike at your home.

Anecdotal story:  I had a pair of Vienna Acoustics towers that were at my home for a year. Really nice furniture indeed! And super cool see through cones (woohoo). I delivered them to a gearhead buddy and hooked up a pair of bookshelf KLH turds before my new Brystons arrived. What a hoot !  The Best Buy KLHs sounded "almost" as good as the Vienna towers at lower levels (muddy as dirt at a bit higher volume- no surprise there) Point being that price and sound are not directly corollary. 

Anyhoo...go on a listening tour with your most demanding source material then get your 2 favorites home and audition them there with you most demanding source material. No regrets afterward. Just wonderful music! 

Any speaker that don’t feel unstressed at 105db is out of the question.

Go listen at a dealer if you can. I was able to do that but a big part of my decision to buy was the universal praise from people on this forum and WBF. If so many think the brand you are looking at are great then some of them must have a room similar to yours and you can be confident the should work in your room. Good luck!!