The most tower like stand mount under $4k

These JA Prisms check all your boxes and come in under your price target. They reportedly offer a lot of the performance of their pricier sibling the widely-acclaimed Pulsar at a significantly lower price point, which makes it a great value in my book. There are some reviews out there you can check out for further info.
https://www.usaudiomart.com/details/649979290-joseph-audio-prisms-black/

Best of luck.

Take a look at Vandersteen VLR with Carbon tweeter. Detailed, not clinical. Very musical. $3291.

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.

Ref 3A de Capo vs the Ref 3A  Episode BE

I think you need to reevaluate your definitions a bit. Tower speakers are not necessarily more accurate, musical or anything more than standmounts. Some may have a deeper bass or fuller bass because of the larger cabinets, but that’s not necessarily the case either.  Second, a standmount speaker on a stand may not take up any more floor space than a smaller standmount. If you’re looking to put them on bookshelves, that’s another story, but unless you buy a speaker made for that, like Wilson Duettes, you are really compromising the sound. 

Look at stand mounts with a passive radiator or larger cabinet to give you a full sound and tower quality bass.  

mofi sourcepoint 8 have a huge sound

buchardt audio s400 has very good bass

deftech D11

legacy audio calibre (used if possible, awesome)

The speakers I own are the most musical in your price range.

Fritz Carrera 7 BE. New $3,500. Used $2,500. 30 day home trial.

Buy the Dynaudio 20 stands from Dedicated Audio (deal) and bolt them together.

After that I would look at the Paradigm Founder 40's.

I had 19 different models in my home prior to Speakerfest 2022

last August. MSRP was capped at $3k so the Fritz were not included.

Philharmonic $1,900 bookshelf won the event BTW. 

I have the Revival Audio Atalante 3 monitors and love them. It took all of 3 minutes to adjust to the bass I miss from my JBL 4319s with their 12" woofers. That's how convincing they sound in the lower end. 

They're even more revealing and detailed than the JBLs but with none of the edge or bite they can exhibit. The designer of the Atalantes used to head speaker design at Dynaudio and before that, Focal-JmLab. Most of their award winning designs were done by him.

The best part is the price: $2550 and a 10 year warranty and they're designed and made entirely in France.

All the best,
Nonoise

Those are kindo sweet

you get much better quality with monitors on a limited budget (with most brands). 3K, used is the sweet spot of great speakers, I have a database of them.