This thread makes me happy.
If you can answer one class as always being the best DPS then me and the other devs are not doing our jobs.
Best DPS should depend on the fight. Resists/AC/Duration/AEs/Abilities etc etc etc should all switch around who gets to be top dog DPS.
Sometimes a rangers melee from afar wins out, sometimes its safe enough for a rogue to run in and do all he can, sometimes resists are low, sometimes resists are high, sometimes whirlwind destroys melee DPS, sometimes an AE makes it hard for casters to chain nuke and on and on and on.
If you want to be big DPS the choices are Necromancer (Good on long duration low resist), Rogue (Good on low ac and low proximity danger fights), Rangers (good on low ac and high proximity danger fights), Mage (Good on 2 mob fights with low resists and low proximity danger), Wizard (Good on low resists and short duration), and Monk (Similiar to rogue but trades lower DPS for more resistance to proximity danger). Obviously this is ultra simplified but it gives you an idea of the spectrum.