i am enjoying immortal but yeah i agree. if you want a full fat no bullshit diablo experience then D3 is the way to go. D2 isn't terrible but for a lot of people is a nostalgic thing. I never played it when it came out and tried the remake but it doesn't do much for me.
immortal is simple, fun, and has the basic diablo gameplay. perfect for a mobile game. i kept going back to D3 but i had played it too much and didn't want to grind a lot. to be fair i'm not at a point in immortal where i feel like i'm grinding or feeling the need to buy anything to progress.
it's almost like you don't know what a mobile game is but i'm sure you do