I saw this thread but really didn't feel qualified to answer it. That was until I found this
Diablo III Review and now I'm pretty convinced as to which is the superior video game. I am going to go out on a limb and say it is better than Tera. I mean if you just look at the system requirements, the lag is low. Also the classes look much more interesting than Tera offers. I mean Tera is a WoW clone, at least D3 is a 2D WoW clone so it is somewhat different you know? Also I think Diablo 3 will have more players and more of my pals on it than Tera would.