Good:
The standard is set with BattleNet. An online system, constantly monitored to keep hacks and cheats to a minimum.
Bad:
So many idiots and trolls, along with thieves and scammers to prey on the former, and baiters to feed the latter, BattleNet is a notorious cesspool that is that way only because nobody can think of an appropriate IQ/integrity test to restrict admittance to the servers.
Good:
You can play online, with up to seven other friends.
Bad:
More hacks than a Conan story; play only with friends.
Good:
No multiplayer.
Bad:
No idiots to deal with. Wait, shouldn’t these categories be reversed?
Good:
You can play online with your friends.
Bad:
Hacked to heck, and legit servers are rare.
Best clone in this category: Yeesh, nothing can match BattleNet; no winners here.
Overall
All the good clones have merits, but Titan Quest is the best Diablo 2 clone yet; granted, the lack of a BattleNet-equivalent system to prevent cheats keeps it from being as dominating. Nonetheless it’s your best diversion if you’re just not in the mood to complete all five acts of Diablo 2 yet again.