Hardcore is infinitely better. Knowing you have to be at least a BIT careful when fighting that lightning enchanted boss makes the game so much more satisfying. It did suck when some ass munch invited you to a party and proceeded to gank you with the hydras.
As a funny aside, some guy tried doing that to me, and the second I saw the guardians I hid behind a corner just as he went hostile. I then went back to town. He was "LOLing" me like crazy, until I told him that he had nothing to laugh about since he couldn't even PK me with the cheapest character possible.
I also remember my friend having a barb that was so powerful (thanks phat l00t!) that it seemed he could not die. Some high level sorc came into a game and started trying to PK, so he jumped into his barbarian. IIRC it had insane life leech, lightning absorb (he loved fighting lightning enchanted bosses, as it actually healed him), and max resistances to every thing else. He could pretty much solo the Arcane Sanctuary while only having to be a "bit careful" when the mass iron maiden casts came up, as he would do a slight amount of damage to himself. While the Sorc stayed too close to town and would keep hiding before getting killed, my friend took no damage. It was hilarious watching two 90s go at it and the hotshot PKer was reduced to cowering in town.
And IMO, the only reason why someone would want to play an open battle.net player is because they want to cheat (or at the very least don't mind it at all, and want to play their LAN characters online...but this typically results in you playing with only friends).