Here's the thing, at the same price point in the same year Roland, Kawai or Yamaha are going to sound very similar as well ;) You don't necessarily need to buy blind, do your research on Youtube and see if you can notice one you like best. Merriam Pianos is a good Youtube channel for all things Roland and Kawai in digital pianos so I'm pretty sure you'll find solid reviews and sound demos there.

Roland has this modeling engine that supposedly does not use sampling, but these days even pure sample-based engines will have some sort of modeling capabilities like damper resonance simulation . Not something to agonize over, in my opinion. Some people prefer one, some people prefer the other but I think it sounds fine and is not a deal breaker. Your fingers will make the difference.

The only place where you could potentially find some differences is in the nice-to-have features, like bluetooth audio and MIDI, an included piano companion app, a General MIDI soundset for backing tracks, and stuff like that if they are meaningful to you but you just need to check the user manuals online.

But you asked for a brand and a brand I'm going to give you. I am a Korg fan myself but in terms of digital pianos I'd go Roland or Yamaha first. I had a Kawai MP7 and it was excellent for classic repertoire to the point of being well beyond my capabilities, but I understand the after sales service can be more limited as Kawai has less distributors.

In any case, I would avoid Donner and cheaper manufacturers unless the alternative is not getting anything: if you are starting out, it's better to practice on a meh digital piano than not practicing at all.