I found Doomspike to be more effective, but that's just me since I hate the animation lockdown you get on Chaos.
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From Carraway's Guide (good tool, read it):
Single-target DPS
Speed Surge II
Auto-attack
-> Invigorate II
-> Pierce
-> Heavy Thrust
-> Full Thrust
If buffs are available and TP>=2000~ and target is <20% HP: Chaos Thrust
If buffs are available and TP~3000: Doomspike II
If buffs are not available and TP>=2500~: Doomspike II
If buffs are not available and TP<=2500~: Chaos Thrust
Trash DPS
Speed Surge II
Auto-attack
-> Invigorate II
-> Pierce (column)
-> Heavy Thrust
-> Full Thrust
If buffs are available and TP~3000: Doomspike II
If buffs are not available and TP>=2500~: Doomspike II
If buffs are not available and TP<2500: Leg Sweep / Heavy Trammel