On the subject of the other dw games:
There are a number of aspects about dw2 and 3 that I greatly enjoy.
I love the core concept and game design ideas of 2. Building a party of digimon and exploring labyrinthine dungeons is great. As a kid I loved it as much as dw1. The soundtrack is great.
Dw3 has some fantastic overworld sprites and music and is probably the easiest to understand how to play, by virtue of being the most traditional.
However over time I have come to view them as not only very flawed in their own rights, but in specific ways that make me prefer the first game by a good margin.
Dw1 can be very tedious and grindy. However that pales in comparison to the slog thst dw2 often is. Because of how the level cap and dna digivolution systems work, along with how slow paced the game is thanks to its overly long battle transitions and animations, makes it possibly the grindiest rpg ive ever played.
It doesnt help that the dungeons are not nearly as cool as i remember them being. For a long time every dungeon has the same boring brown hallways, its several hours before you see anything different.
It's a game that could have been great but suffers immensely from a lack of polish.
3 has a very obnoxious encounter rate and is extremely unforgiving when it comes to exploration. This is because you can get punked really easily if you step into the wrong place, some areas have digimon much stronger than your party with little warning. Unlile dw1 where you can run or avoid visible enemies, this is not the case here making it much more difficult to avoid these situations.
However the real problem for me with both games is that while they are both more intuitive to play, they are not nearly as unique or interesting as dw1. This especially applies to 3, which is basically like every other b to c-tier jrpg released for the playstation.
That's not to say these two other games dont have their merits or that I don't understand why people might prefer them. It's just that as ive gotten older i feel like they are all very flawed anyways but even with that, dw1 is still by far the most worthwhile because of all the reasons ive spoken about already. I cannot bring myself to revisit 2 or 3, they are way too long. Dw1 is not only more compelling but can be beaten in a far shorter amount of time, which makes it easier to replay.
I have no opinion on dw4. I heard it was bad, but i have not played it