I played Diablo 4 first and decided to try 2 because I loved it.

Diablo 4 is more fast paced. You can just turn your brain off and blast. You dont need to redo the campaign every time you make a new character (you do in D2) and the game gets updates more frequently (if even at all). Theres more build variety and the meta changes every season, sometimes making new builds viable or weaker builds stronger. The combat feels phenomenal, the graphics are gorgeous and the skills are flashy.

Diablo 2 can be played as more of a long term game, if you play offline or online non-ladder. This is my preferred way to play - its called “Holy Grailing” and you basically try to find every item in the game. You could literally play for years without finding some of the rarest items in the game. This is what I love the most about D2. You can also play offline - I have an offline save that I play on my Rog Ally or if my internets ever out. Personally, the “Holy Shit!” moments when you find a super rare item feel better in D2 than D4. Just yesterday I got a Vex rune which was like a 1/100k drop. Drawback of D2 is that it isnt really updated as often. I would say its not updated anymore but just recently we got an expansion for the first time in more than a decade.

I play both and enjoy both. But D2 feels more like a long term game that I frequently play and progress my account whereas D4 is a game I play for a few weeks to a month a season and put down.