First of all d2 in general: It's like a goddess that you slowly get to know when playing and thus you get to know her flaws. And those flaws make her even more beautiful. I don't wanna know how much I raged in cLoD because the server simply decided to disconnect. So the base engine despite its flaws is also very nice due to complicated mechanics. (For example when there are too many items on the ground and you walk through a tp--> connection lost. It's a reason to rage, but you simply accept that it isn't perfect and you make your way despite all those bugs which feels like an even better achievement.)
Now to MXL:
- You have tons of mechanics that aren't easily seen right from the start. For example how poison damage works. Or how CB works, how magic damage works or how doom works with ttad... you get the idea. Simply by getting more knowledge about the game you can become greater and adjust your playstyle.
- You can share this wisdom of yours and help newbies. This is not some game that you can just casually play without putting in some effort. This is very rare in our time.
- There are tons of viable builds. Some may still lack a 100% balance, but it's getting better with every patch.
- This is a game where a summoner is viable (my favourite class). Another thing that is very rare and I have yet to find a game that has a viable summoner gameplay (Except Nekro... but well... it's a game where every character you can play is a summoner.... so I guess it doesn't count

- You have tons of oskills. So skills you can't naturally cast right from the start. And some of them are really good. Making builds around those skills is fun and shows the depth of the gameplay.
- you have tons of procs. Something I find lacked in cLoD. But procs are fun. All of them. Which game ever used procs? cLoD maybe, but there weren't many procs that were useful.
- you can craft and create most of your gear that is necessary for a further progress on your own. You don't just join a baal run and have to wait for an item to drop that is very essential for your build. If you know how, your progress won't stop.
- it's a small community. Those are in general more like a family. People aren't stressed about joining a game and finding themselves to be flamed by 4 other people (like League of legends for example). And that keeps the fun. You have to help each other and you can do that due to group buffs. Another thing that not many games have in this variety.
- the true endgame gear can improve your character a lot. The better the improvement, the better the experience of progress.
- Some builds only start to get better after you reach max level (for example: broadside sin) but that's no downside because your merc can carry you through the game.
- Every build feels different and requires a different strategy to get through the content. This is something I really like because that way you have a variety in the game like nowhere else. Even when there are 2 people playing the same build, they both can have a different usage of skills, so there's even a variety to items/skills/playstyle within the same builds.
- the endgame content. I'm so happy you don't have to do thousands of baalruns, where you basically just hide behind a pillar and let other people do the rest. No, I like that the game starts only when you reach max level.
- the endgame content (again). Tbh, I never put much thought into the universe of Diablo simply because the games were never meant to give you much of a story. But MXL basically pulls you through all of the history of this universe and makes you fight special bosses. So there is still some background as to why and who you fight. For example you fight a siege weapon created by Mephisto (DP). I love that lore
I could list more, but I don't want to end this thread with my post
