Choosing a speaker first may be a good direction to take, however making that choice should and really must involve some serious auditioning. If it were me attempting to make my speaker choice FIRST, and assuming that I discovered a set of loudspeakers that really "rang my bell" (assuming that the audition involved some music and recordings that I enjoy and am familiar with), after the audition, I would make careful note as to the exact components used in the audition. Next, I would attempt to locate another knowledgeable brick and mortar dealer that has the same speakers but is recommending different system components to drive them.
This approach gives a person an opportunity to determine how those speakers perform with a different set of variants. If you come away from audition two, with a satisfactory conclusion, than there is better than a 50/50 chance that you will truly be satisfied with the purchase. Especially if you choose your components as a
"post facto" approach, and of course, select components by reputation and hopefully, by audition.
Frankly I have found over the past 30 years or so of working with a wide range of audio reproduction components at all price levels, that most people I have run into tend to do their selection process in reverse to what you are planning. Honestly, I can't authoratively say either approach is the best road to take.
One thing I can inequitably say and recommend to you, is to "stay away from audio shows as a definitive way of making component selections".. Frankly, I haven't heard an audio demonstration since the late 50's at a major audio show, that really" rocked my boat" and has stuck in my mind all of these years.
I noticed HARBETH as a recommendation. HARBETH is very high on my list of top speaker choices, but - - - I consider HARBETH a musician's speaker. Classical and Jazz sound incredibly realistic, (depending on room setup) They are not necessarily the most likeable choice for a person who has musical tastes in the direction of "ROCK", FUNK"; ABSTRACT MODERNISTIC SOUNDS, etc.. Especially to a person who prefers disproportionate, over driven bass reproduction.
There are a lot of fine speakers out there depending on taste. {Choose wisely grasshopper")