Fire - Immolates. (stacks for longer duration, I once got 9 hours of immolation!!)
Frost - Holds for long periods of time. Make sure you set a high wimpy.
Acid - Blinds and sometimes softens.
Gas - Poisons, does an organ-disrupt style maledict (vomiting) and does the most damage out of all of them (cloud giants, give up now)
Lightning - Arcing lightning (stacks for longer duration)

They also break voker shield that make you immune to them quite regularly, meaning you have to flee/recast every other breath.

There is a chance with all of them of getting a malison (vuln) for whichever breath you're being struck by. Getting a long immolate with a fire malison is not cool - it does decimates unprotected. Malisons also override whatever resistances you have.

Taking the dragon hunting edge, and stacking on svb seriously helps against all the above. Voker shields and/or resistances are not enough alone anymore.

Even in their current form, they are far, far preferrable to their previous versions :P

Yhorian