I would have to call someone an idiot if they said Diablo 3 is better than Torchlight 2. It isn't even worth comparing. Diablo 3 is a garbage game designed around the RMAH. Torchlight 2 is what Diablo 3 should have been had Blizzard not been so greedy.

As far as comparing Torchlight 2 to the original, I would say that if you liked the original you will definitely like Torchlight 2. A lot of the same stuff is in Torchlight 2, such as pets and fishing (where you catch fish that transform your pet or give it bonuses). I didn't really play it long enough to say anything other than it seems like a very well improved version of the original.