DPS for class XFollow

When DoT stacking, most spells will stack. Certain things prevent stacking, such as non-damage detrimental effects: snare and debuff being common culprits. For example, a necro can't stack Dooming Darkness and Embracing Darkness, since they both have snare effects and Embracing will always prevail (as the higher spell). Heart Flutter/Asystole are disease-based with AC/Str debuffs and won't stack. Just damage spells, like the fire and poison lines, will stack.

Necros are the tops in the DoT category (and sometimes for total DPS). SKs have similar spells; Shamen and Druids (and, to lesser extents, Ranger and BST) also have some DoTs.

What you need to consider is duration of spells for total DPS. Since they're stacked gradually, the damage can peak like a bell curve. As a necro I've done some parses, and let me tell you, it's pretty sick. So much so that the necro community in general does not divulge accurate DPS reports, since most other classes would (and generally do) consider their sustained damage grossly overpowered.

As for specific classes, try looking for class message boards. I go to EQNecro.net and Necrotalk.com; there's the Shaman's Crucible, the Druids Grove, etc. which will have discussion on their spells, occasionally focusing on DPS.

Typically it goes Rogue, Zerker, Wizard, Ranger/Monk/Necro, Mage, Warrior, Beastlord

That is very true, melee DPS is very very very much gear dependant