I played D2 recently, without any mods - basically because just like you, I didn't want to play something like Meridian or Eastern Sun which completely changes the game. So I played unmodded. I only regret one thing: Not using PlugY. Keeping two accounts and constant muling is such a hassle, and PlugY also has other features that might be nice. I've never used it, but seen it on some streams (Teo/MrLlamaSC), and next time I'm going back to D2 I'll install that.
I can't give you a link or guide for installing that (plus I think technically it's third party application so I'm not gonna post it anyways), but it should be easy to find.
There's a ton of other mods but I feel many of them go to far. Also note that mods will get you banned if you connect to Battle.Net, so keep a "pure" installation in a separate folder. However, since streamers play mods and Blizzard even used modded D1+D2 screenshots at Blizzcon, I guess it's an acceptable grey area to talk about them.