They're still in the same sub-genre and the core mechanics are very similar. I wouldn't call them apples and oranges. More like red and green apples. It's not much of a party in Dungeon Siege either, you may have more followers but all they do is charge forward and kill everything like in every other hack'n'slash / action RPG.

As for Dungeon Siege 3 I enjoyed it a lot more than I thought I would and yes, I hope they find new ways than potion chugging, that's neither a fun or interesting mechanic especially when you have to wear like a 100 when you are going into a dungeon like in Inquisitor.

The system in Path of Exile sounds quite interesting, luckily I still had my beta account working so I'm going to give that another shot.

Alright, but with red and green apples, I have a clear winner: I prefer red apples :-)
Whereas with Dungeon Siege 1 and Torchlight, I like them both and won't say one is better than the other (I am more replying to ashout in post 14 above).