Acoustic Suspension sound in 2020?

Some AN models are ported, some are sealed.

IME, there is really no substitute for the acoustic suspension sound in a vented box. Some bass-reflex and transmission-line speakers can play as deep but lack the speed and texture. Open baffles excel at texture but can’t dig very deep. The advantage of bass-reflex is reasonable efficiency with decent extension. AS designs tend to be power hogs but excel in bass quality.

Old models like the Large Advents can match and even surpass some modern designs in many regards. Unfortunately, I find they sound great until they suddenly don’t. They suck up gobs of power and there’s a very sharp transition from clean sound to ugly distortion. Playing them at loud levels can heat up the motors quickly and lower the threshold further. This is why I don’t use my NLAs above moderate SPLs, however, played within their limits they can teach modern designs a thing or two.

The Gershman Acoustics AS designs are intriguing, though I’m suspicious of their claimed sensitivity:
http://www.gershmanacoustics.com/gershman_speaker_modles.html

Most ATCs are acoustic suspension.

In the budget realm there's NHT.

Vandersteen, which were modelled in part after the acoustic suspension sound. 2ce Signatures and model 1c are acoustic suspension designs, maybe other too.

Vandersteens are not acoustic suspension speakers. New acoustic suspension speakers are few and far between.  Magico and ATC make acoustic suspension speakers.It’s too bad there are not many more than that!

If you like the East Coast Sound of acoustic suspension speakers of the 60s and 70s, I would suggest you look for a good condition vintage pair of the AR, KLH, or Advent speakers that you mentioned. I am not aware of any modern speakers that replicate the sound of these speakers. If you want information regarding specific AR or KLH speakers, I would suggest posting on Audiokarma. There are many East Coast Sound speaker enthusiasts on that site.

Acoustic suspension is still the finest in overall bass quality and lowest distortion. Caveat: If properly done.

The end.