You have a lot of options and that's the problem.
Typically any modern digital piano from a "reputable manufacturer" like Yamaha, Roland, Kawai, Korg, Casio, Dexibell etc. will sound pretty good just based on the piano sound generator. The amount and implementation of the various resonances found in a real acoustic piano vary. They aren't that crucial but will in part affect how "acoustic" the digital piano sounds.
Then come the speakers. There's everything from "muffled" and "distanced" to "OMG it's so real!".
Typically the more expensive models have the more elaborate speakers systems. And typically they are "cabinet models". But a "portable" or "stage piano" could also have pretty decent speakers like maybe the Roland FP-90 just as a hypothetical example.
Then the key actions vary. There are things like noisiness and looseness or "wobbliness" that anyone can experience and then there are finer nuances that take a certain skill level to judge.
One is the infamous "pivot length" that's often mentioned here. On the Yamaha PSR is much more difficult to play the keys from the hinged end. This also applies (less dramatically) to digital piano actions with a short pivot length like Yamaha's GHS and most Casio's actions. But it might not really be a problem for you. But it's something to try out if testing digital pianos in a shop. And then you'll look very knowledgeable.
Then all the others like "escapement" or "let-off", counter weights, wooden keys and such are less important. And even ignoring all these fancy words in the specifications the playing feels just do vary. As do people's opinions. Some like e.g. the "RH3" action found in the Korg C1 and others don't.
If not playing with headphones the speakers will actually affect the playing experience quite much. For example a Korg G1 Air apparently has a better speaker system than the C1 Air. And similarly a Kawai CN37 (or 39) has a better speaker system than the CN27 (or 29). And a Yamaha CLP-645 has a better speaker system than a CLP-635 etc. And you typically won't hear the differences on YouTube videos and such.
Anyway there are an awful lot of models to choose from.
For around $2500 and below there are e.g.
- Roland DP-603, a compact version of the HP series that's an upper market range from Roland.
- Yamaha Clavinova CLP-625, the cheapest model in the Clavinova range that's above Yamaha's "Arius" range
- Roland FP-90, a higher end portable piano that optionally comes with a stand and a pedal bar
- Yamaha Arius YDP-184, a high end Arius model, not necessarily any "worse" than the CLP-625. Yamaha may have some overlap here between those two ranges.
- Kawai ES8, a higher end portable piano that optionally comes with a stand and a pedal bar.
- Kawai CA48, the cheapest Kawai with wooden keys.
- Yamaha P-515, a higher end portable piano that optionally comes with a stand and a pedal lyre.
- Roland FP-60, a little "lesser" portable model compared to the FP-90.
And now we are already under $2000
Then the list would go on to even cheaper, but still "perfectly fine" models like Roland RP-501R, F140-R, various Casio Privias and Celvianos, Korg G1 Air, Yamaha Arius YDP-164 and whatnot all the way down to around $500...$600 which would still get you "something usable". A cheaper option from that range like Roland FP-30 or Kawai ES-110 would serve you just fine for many years if only the speakers are okay and not too muffled.
(I guess. But take any internet opinions with healthy scepticism.)
And then there's the "fun factor". Some models come with lots of various sounds and backing rhytms. They can be fun. But then you are not "playing piano" anymore. Yamaha has the relatively cheap DGX-660 and Casio has a few Privia models with backing rhytms. The Roland RP-501R and F140-R also have some. (Many other Rolands also have, but you'll need to use their Android/iOS app to activate them.)