Not trying to sell anybody on anything. If you scour hard enough, you'll find somewhere that I said 2-way can be done exceptionally well, and 3-ways can be done poorly.

Everybody has their preference, though, and mine is a well executed 3-way.
For me, I would put my money on having towers that are as close to full range as possible with very good mids and highs, as well as having subs, because the more solid LF sources you have in the room, the better your overall bass response will be. My personal opinion after auditioning the DTs, and other speakers, more and less expensive, is that they didn't sound good. Period. I would not want to listen to jazz, orchestral, rock, or hip hop on them. I am a music first guy, Half my life was spent with a sax in my mouth, on stage and off. In my audition, they did not reproduce those sounds in a manner befitting the cost.
Add to that: inaccurate specs, the cost of building amplifiers into the speakers, and Atmos modules which most agree are the least best option for Atmos...
Again... This is me. YMMV.
For the cost of either of those options, I would have spent in the middle for Monitor Audio Silver 500s. Of all the speakers I auditioned, up until I heard the Philharmonics, Those were my favorites, followed by Martin Logan Motion 60XTs. I listened to two different KEF lines, and if not for them causing listening fatigue for me, I would have considered them, too (They both sounded nice, big expansive sound, but something about that Uni-Q driver and my ears didn't get along.)
So yes, can do three bookshelves, 2- towers and a bookshelf or center, 3 towers... Especially when paired with subs!
I would urge you,
@Aman, to go listen
WITH your friend. If possible. If he hasn't ever auditioned speakers before, you should give him that as a gift: your experience with audio. If he really likes the sound of DTs over anything else, well, at the end of the day: Its going to be
his system.

It didn't slip past me that you are looking for a way to steer him away from that choice... Am I right?

Consider, By themselves, those ULTRA Bookshelves aren't going to stand up to the DTs, whereas the towers will.
My 2cents.
Cheers!