My personal ranking of the 4 games from best to worst:

This is going to be controversial but here we go:

Diablo 3: I love the classes, the grind, the story is poop but the skills and classes are so much fun. Best armor sets, so many difficulty levels, D3 is just crazy chaotic fun. It's a more arcade style Diablo but thats fine. It's just pure fun. The game never takes itself seriously and you never have to worry about picking the wrong skills or messing up your stats. It's just a grind for epic loot and that's fine. That's all i desire, To feel like a demon slaying God, and D3 does that.

D4: honestly after playing D4, I see the appeal. I was skeptical at first but the classes are solid. Gameplay is addictive and fun. It's just the open world aspect and the always online that hold it back. And the egregious monetization/battle pass system, but if the game ever gets an offline mode + a complete edition with several expansions it could overtake 3. The skills for the most part are well done, the enemy variety is good. The potential is there as long as Blizzard doesn't focus on the monetization aspect.

D2: I LOVE D2 and im not bashing it. But the gender locked classes, the entire act 2, stamina system, it has flaws. It's only slightly lower then d4 due to those reasons, D2 is a fantastic game and it's the one I grew up playing. But it is also VERY grind heavy and build determinant and there is barely any sidequests to do. It felt like an expansion to D1 and that isn't bad, it's just dated compared to later entries and what they do better. I was playing D2 earlier, I love the game but I am not going to look at it with rose tinted glasses. It's rough even with Resurrection. Its VERY easy to mess up your stats or pick the wrong skills. The game is still a masterpiece but you have to know what you're doing to fully enjoy it.

D1: Diablo 1 was my introduction to the series and while I love the aesthetic, it's very dated in terms of gameplay and design. If I had a PC I would still play it, but again compared to later entries its very lacking. With only 3 classes, a linear adventure system and a lack of magic/skills and armor sets, there just isn't much to do except grind and get to the bottom. I still believe the game is fun but given the choice, I'd prefer later entries.