What DLC to buy/in order?

I played D1 years ago, and I believe I even played D2 the first year it came out on console. I haven't played since and am now on PC.

I can see the game is free, but there is currently a Steam sale so I'd like to buy all the DLC as I'd like to get back into the game, max level, raiding etc. Can you explain the order of DLC, what they contain, what I need to buy to own everything etc?

Feel like I was having this issue when trying to buy Hitman WOA... apologies if this has been asked a million times before.