Priority is better for revenge killers. These Pokémon have enough bulk to live a hit and damage their opponent into KO range of their priority. The strategy goes like so:
Turn 1: Tank a hit then attack, hopefully getting the oppponent into the red or lower yellow HP bar.
Turn 2: Use priority to outspeed and KO your opponent.
The second type of revenge killers are those who rely on Sturdy or a Focus Sash to revenge kill. The strategy goes like so:
Turn 1: Attack then tank a hit/hang on with Sash or Sturdy.
Turn 2: Revenge kill with priority.
Good examples of the former priority-abusers are Azumarill and Mega Metagross. Good examples of the latter are Mamoswine and Crawdaunt. Priority is usually best on those who can live long enough to use it.
Hazard setters, while usually bulky, do not have to be. Garchomp and Smeargle are examples of frail hazards setters, relying on the Focus Sash or a plethora of resistances to get hazards up. Bulky setters, such as Gliscor and Tentacruel, are also viable. Hazard setters simply need to be able to either force a switch (e.g. Garchomp forcing out an opposing Heatran), live a hit thanks to their bulk (e.g. Ferrothorn), or act as a one-trick pony and rely on the Focus Sash to get hazards up (e.g. Smeargle, Galvantula).