If diablo 3 is anything like 1 and 2, mobs will attack whoever is closest that hit them last, not who dealt most damage.Aggro is normally held by dealing the most threat. As far as I know, no Diablo 3 abilities deal extra threat because they're designated "tanking abilities". That would mean the only way to hold aggro is to deal the most damage. If, however, you make a "tanky" character, wouldn't that by design mean it will most likely not deal the most damage?
So, usually the barbarian or monk.
Correction, diablo 2 could be soloed with /players 8 from level 1 to 99.Remember, Diablo II could easily be solo'd infinitely if you had the gear. If you did not, you were better off hanging around people that did. Since you cannot flee games up-on near death in DIII, having a tight group is probably the way to go. Until things start exploding and everyone dies in one spot