BAR NONE, these chains are absolutely the strongest bike chains in cycling. Be aware that KMC has sourced these to cheaper manufacturers recently, and the new ones DO NOT have the toughness of these older ones.
X10.93, considered as stretchproof as any out there, but the big deal here is that they are SO HARD to break. You will see this when you have to break that pin when sizing a new one. On the bike I will typically break 10 shimano or Sram chains for every ONE of these. They are truly that much better, especially if you are a hard shifter, like me. These come with that very sticky silicone like coating. The newer ones are just mineral oil, don't buy them. 116 Link for ANY application. These are the only chains I stock because everything else is inferior.
Silver: $39ea for 2, 49 for 1.
Gold: Ti coated, $69ea.