The most tower like stand mount under $4k

The most refined and balanced speakers under 3k I’ve heard was Amphion Argon 3s.

Most musical was probably Triangle Comete 40th Anniversary which I actually had last time, though the mid was colored and the bass needs a sub to support. 

Not in your price range new, but used they fit in your budget. Great bass for a standmount speaker and the ribbon tweeter is the same in all ProAc speakers.

A better description of your system would be helpful. ProAc speakers are generally amp friendly

https://www.stereophile.com/content/proac-response-d2r-loudspeaker

Well probably a 3 way would be closest to the norm tower speaker. Little less bass because of cabinet volume etc.

KEF has one I believe, Tekton Impact Monitor, Paradigm S4 (older) but kick ass, I think Salk makes one.  uhhh I’m sure there’s more but not as many as you might think.

I’ve owned the Falcon IMF-100. You can get the kit or factory built for under 2 grand shipped ( no tax). They are sold factory direct only. They are a Transmision Line design. I received them in less than one week after placing order.

IMF 100 “Complete@Home” LOUDSPEAKER SYSTEM (falconacoustics.co.uk)

Review!

https://the-ear.net/review-hardware/falcon-imf-100-standmount-loudspeaker/

KEF R3 Meta bolted onto their bespoke stands, My dealer has told me since the original R3 was introduced that "the R3 is the best-selling floorstanding speaker that's not a tower" he's ever offered. And sold a LOT of them.