Both are quite similar..

The both have that cartoon action, level up and RPG elements, the price is about the same and both seem like alot of fun. Torchlight got a class system which might give the game a bit more length if you seek to level up all classes, DeathSpank however seem to be alot bigger and longer, and have better quests.

EDIT: Oh.. and which one should i purchase?

Torchlight is basically Diablo, I believe it also has randomized levels (replay value...) and it's on sale every other week on Steam....

Death spark doesn't seem to be on PC (vid says XBL PSN)... so i'm guessing the game is much simpler... the vid looks fun though. However the evnironements don't seem to be randomized so i'd guess this is the shorter game...

They're both good games.

I prefer Torchlight over Deathspank because the loot and inventory system is much more streamlined and engaging (You also get a doggy!).

Deathspank is funnier but the fart jokes get old after a while.

I would choose whichever appeals to you most.

Edit: Also I would say that Torchlight is actually a bigger game than Deathspank from what I have played of both (I could be wrong though as I've only played  5 hours of Deathspank) and the comment that "Deathspank has better quests" is false as they are all pretty much "Oh, I lost something Somewhere. Can you please get it for me?"

Edit: DP(Double Post NOT Double Penetration)

I played Torchlight and liked it, but it didn't caught me as Diablo 1 did. It was more like Diablo 2 in feeling, I don't know why, anyway. Gave it up, never went back.

The other one seems funny, art style is funny, more colour, more open...I would go with DeathSpank

I've had a great deal of fun on Torchlight so I recommend it. You missed some great opportunity to catch it a great price during the Steam Summer Sale :D

Yeah i know.. it was at 5€ or something like that before :(