$3500 floor standing speakers used. What would be your choice ?

What is your current speakers and venue? Would be helpful to see them. It is easy to create a virtual system with a few photos... that would be really helpful. What are yours tastes in sound?

A nice combo would be the Devore Nines, the original, not the new Super Nines. They lack a little transparency compared to the newer ones but it your not needing the last bit of resolution (which you won't get at $3500) keep your eyes open locally. They seem to go for under $3000 easy. 

I would search between 5 and 7K speakers used

https://speakerchoices.com/

Current speakers are Michael Green Audio Rev80i free resonance design. Let's say their sound signature is close enough to Grado RS-1 wooden headphones. I play at moderate levels, many kinds of music but not hard rock or big orchestras.

I don't tolerate bright or "stupid" hi-fi kind of sound. Midrange must be right or I won't listen. Going down confidently to 35 hz would be enough. Soundstage is very important, the space should be "heard" and felt.

@inna Ah, brings back some fond memories. I had a pair of MG Rev60’s many years ago. A very nice speaker using classic Vifa drivers. Learned a lot about proper loudspeaker set up with that little floorstander.

Highly suggest you check out Tekton. Eric has many options in your price range. I think you would be floored by the performance of his speakers.. They would exceed your expectations by all the criteria you listed. See the parallel thread/review just posted by teajay on the Tekton Encore monitor. Then go to Eric's website to see his bigger offerings. You might do well to give Eric a call given the many options he offers.