nightcraw1er.488: Well, I am wondering why it is these two in particular? There are a lot of very good arpgs on here and elsewhere. Tq is pretty good, quite long and has some variance. Gd I have only been through once, and again pretty good. I would personally get both, but if I had to, TQ at the moment. GD is currently on the dlc mode (crucible recently) so save money and get the collectors edition in some time.
Also note, other than the other games, there are a load of mods out the for Diablo 1/2 and TQ, I currently don't know of any for GD.
It is about one game vs the other, not about the whole genre. It is interesting topic for people, who are indecisive about which game of the 2 or 3 is better to try, which is longer, which has more loot, etc. There could be topic :"Titan Quest vs Viktor Vran" or "Grim Dawn vs Van Helsing". The point is to compare two games out of many.