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

I have Tekton Double Impact SE speakers and I think they sound fantastic. Lots of kick. Did not have a problem with Eric and had great customer service. I understand those who don’t like him or his products, although I think many have not heard them. I have had Magnepan, JBL, Boston Acoustics, Monitor Audio, Bose and many, many others. Didn’t know Salk went out of business, sad, great company. I am sure if the OP takes his time and listens to many speakers he will find the right choice.

I'm currently considering a pair of ATC SCM40 passive models. I've seen them used for $3500-4500. They seem to be universally acclaimed and reasonable in price. I'll be doing some listening in the next week or two. 

I always encourage looking above any budget, just to know what might be available just above before deciding,

speakers $3,510 to $4,100, 133 listing in usa

Kind of hard to recommend speakers when you don't say what you have now, what you like about what you have, and what they are lacking. Also the room size, placement, listening volume, music type and what you expect out of new speakers. 

You only have 60w, that might not work with a lot of speakers if you like high volume. That also gets rid of any electrostatic speaker. 

Also, if you are very happy with your current speakers, since they are over 20yo, why not just referb the crossovers? It will be cheap, and they might sound better then new after. 

Well, after 25 years I might want to upgrade even if I still like the speakers.

Rooms will be changing, that's not part of the equation here, they should sound good in any but very small or very big room.