Chaos is one of the worst damage types in endgame? What?! Great devotions, huge damage values, best augments, does not require that much RR, best Exclusive skill. I do not talk about sets, there is no bad Chaos set in the game (in my opinion). Is it so bad for modern Gladiators? Okay, Reaper can be pretty hard (and sometimes Benn, but he is rather annoying), but that is it.
Bleeding needs secondary Damage type for life-leeching, otherwise it is good, especially against tough targets. Also does not require much RR, scales with Cunning (natural synergy with Physical and Pierce as well). Variety of sets is not great, of course.
Tri-Elemental? Not great, not terrible. Can be useful if built properly (through classes with double RR or big amounts of flat Damage, converted or not).
Physical, Vitality, Aether, Cold, Pierce and Acid types are more or less okay, nothing wrong with them.
The last two are (again, judging from my experience in endgame) unfortunately trash. Fire and Lightning are super-heavy resistant by most enemies, have poor Damage values, percentage and flat (Lightning also has that disgusting 1-over_9999 diapason, incosistent especially for melee characters and their life-leech), double RR does not save you from poor performance (Widow is the clunkiest RR to use, cannot be bound to pets and minions just because ). And how convenient that Grava, one of the worst Nemesis thanks to his pools of “constant missing” and one-shot balls of “run_or_die” mechanic, is resistant to both. So much fun playing a melee character against that perverse creation . The only good thing Fire and Lightning have are good visual effects. Enough said.
I am surprised by poll results. But whatever, experience is so individual. I do not consider Spellbinder and Dervish classes strong, but here they are valued highly, for example.