Situational. That being said:
Hexes are more of a one stop shop, get everything done in a single go and then pulling the heat down. A curse on the other hand is binding a particular woe or situation to a person. I've heard of and used both being used in a variety of ways.
Barring a particular situation.
A string of bad luck.
Any work that you keep working (i.e. poppets, buried jars, goofer dust, etc.).
Now, I can't say that I quite understand what you mean by an elemental hex? I've never personally used Elemental Maic, however, in the case you mean incorporating elemental representations (i.e. salt for earth, hot sauce for heat/fire, etc.), you may consider placing hot sauce in his shoes, or crafting a poppet and applying hot sauce to the poppet's feet. A watery grave could be placing his poppet in a relatively large jar of water, filling it wth pins and glitter and keeping it shaking will distract him and be a figurative pain in his side.