I was a huge fan of Diablo 1 & 2. I played them for years, running around hacking and slashing. Such a good stress relief it was. Then I discovered the item editor and could make my own sets. Personalizing stuff made the game even more fun.
I went on vacation and stayed with a nephew. He had Sacred on on his 3 computers for hosting multiplayer lan games. My son and I tried it out and were hooked. Sacred's free roaming play hooked me. We played hours on end and didn't get much vacationing done to my wife's displeasure. When we returned home I went online to buy 2 copies of Sacred Gold. We discovered Sacred 2 and decided to buy it from the UK with the preorder of Ice and Blood which was due out weeks. All I can say is I was blown away by the game's depth. One thing I really liked was the vast size of the map. The graphics are years beyond Diablo. I was in love again, I bought a copy for my nephew and a few weeks later 2 pretty boxes of Sacred gold showed up (gotta love em for that). I am sold on Sacred 2 and for the CM patch there just aren't words good enough to praise it. I will buy Diablo 3 when it releases. I am willing to bet once the main quest is done I return to Sacred 2. I have Titan Quest and the addon, it came as part of THQ set I bought to get Dawn of War II. It's ok and I play it once and a while.
Oh one other thing I haven't seen mentioned is the ability to hire and equip a partner like Diablo 2 has.