I think it's more a case of "should I get 6% crit or 20% elemental? Which would be better?" which depends on your elemental damage and crit chance/ crit hit damage. There's alot more to building right than just stacking alot of stats.
Yeah but there's also more to building then theorycrafting dps over time. xD You're depending on random drops and you're unlikely to get exactly what you want. And also you can't really have it all so often you're going to have to make a decision and grab CDR over Attack Speed, Crit or Crit Hit Dmg. And for most classes and builds Attack Speed is a stat that should currently completely be ignored except if you get it on like Bracers or Belt.
At the same time the choices also tend to be rather obvious with very few exceptions.
BIS Ring 1:
* Ring of Royal Grandeur - Always comes with mainstat, attack speed and life on hit. So there's not really much choice, optimal here is for it to drop with either CDR, Crit or Crit Hit Damage as 4th stat then reroll life on hit to one of the others that you missed and what you want.
Alternative BIS Ring 1 if you don't need set bonus:
120-160 damage (or something like that)
Crit Hit Damage
Crit Hit Chance
CDR or Attack Speed dep on build.
BIS Ring 2:
* Stone of Jordan - Elemental damage is so stupidly powerful (provided you have good gear) that it's always the best choice. SoJ drops with Primary Stat, Elemental Damage and Elite damage. Optimal is for it to drop with either CDR, Crit or Crit Hit Damage as 4th stat then reroll primary stat (yep rly) to either Crit Hit or Crit Hit Damage.
BIS Ammy:
100 Crit Hit Damage
10 Crit Hit Chance or 8 CDR
750 Mainstat
20 Elemental Damage
Because if you were so lucky that you got a SoJ where you could drop your primary stat, then you really want those 750 points you get from ammy.
BIS Gloves:
If you're fire go elemental damage - mainstat + Trifecta w/ Either CDR or Attack Speed
If you're Cold go Elemental Damage + Crit + Mainstat + CDR or Crit Hit Damage
If you're a Pet Doc - Tasker and Theo's - Mainstat, Atsp, Crit, Crit Hit Damage
Anything else - Mainstat, Trifecta w/ CDR or Atsp dep on build.
Anyhow, Rule of Thumb is elemental damage is always best as long as the rest of your gear doesn't suck and it will scale best as well. Only place where you in a pinch should choose something over Elemental Damage is on neck because 100 Crit Hit Damage > 20 Elemental Damage.