the difference between tanking and tanks is like the difference between routed and routing protocols. tank is a set of speciffic classes, of these, SK and DA do the most damage. but they have to use crystals and have the right tatoos do max their damage. tanking, however, can be done by just about any class depending on the party. tanks as a whole dont do much damage. so if you're looking for a class that can function as a tank in non-raid situations, just pick any damage dealer.
dps sounds like WOW so if you want a tank type class that can do some dmg then the Dark Avenger is number one when panther is being used. Panther has massive patk and does sweet add dmg. Panther does take some of the exp from the DA and cost crystals to summon, but I always use mine. I f you want a damage dealer that can take some hits then a glad is good way to go, they get tough at high lvl's
You might need to clarify what you mean by "tank". If you want a class that is "guaranteed" to hold mob aggro then it will have to be DA, Paladin, Temple Knight, or Shillien Knight. Of these the best general purpose DD is probably SK but some would say DA (if they use the Kittie). But I think if you are after undead mobs then Paladin wins.
However, an option is Destroyer. They are not true tanks (since they don't have hate skills). But in my experience as a Spellhowler a properly buffed Destroyer can hold aggro, just not guarantee it. They can even hold aggro with groups of mobs using a polearm and the Hurricane skill. If you are looking for melee DPS you can't beat a Destroyer. Some would argue that fully buffed you can't beat the DPS of a Destroyer period. This is for sure true in AoE.