If money is not a problem

unless the notion of near-limitless SPL's is the reason for the question, the answer for me is simple- the same speakers i already have. money is not the problem- it's the software- both variety and format- which is always changing, and not always for the better.
that for me is the limiting factor- after you've been in the hobby for awhile of course and have the opportunity to audition what you want, and then waiting and saving.
but for me, really good recordings by the most gifted artists of both classic as well as new music are the last pieces of the puzzle.

getting back to "speakers", many years ago i heard a superb recording of "carmina burana" (the original early music) on harmonia mundi playing on watt/puppy 3/2's. the voices floated around the room with a purity and a "there-ness" i'd never heard before. so i re-iterate that transparency and resolution has been around for a very long while, although refinements have brought about more choices than just wilson audio or apogee's or quad's.
therefore, if you have a nice space to listen in and a Good Recording beautifully performed, then you have already spent enough money. or you can go down to the airport and stand behind 747's when they take off if you want a more powerful experience.