I can't comment on D2 but I regard D3 as one of if not the best dungeon crawler ARPG ever created. It gets so much right, from the constant progression unlocks to the elegant transmog system it kicks pretenders like Destiny 2 to the curb.

I'm probably not the target audience for D4 because I want to be the lone (offline) hero against the darkness. I find this more immersive than the faux MMO system that makes it feel more 'videogamey'.