Champions Galea apart, which, no offense, should be really bloody blatantly obvious what piece is superior for the circumstance(s) you are applying it.
The Shura Z. Kabuto is pretty awesome, STR rivaling the NQ Wyvern Helm, and Acc. +5. I like this for Samurai because occasionally you will use rana and this little extra bit of acc helps and kinda negates the need for a separate WS entirely, obviously excluding HNM, not that Rana is particularly useful with HNM work anywho.
From a monk standpoint its, well, awesome. Great Asurans fists piece if you have an accuracy heavy build, if not O-Hat or Anwig Salade with +15% is probably better. Fantastic Dragon Kick piece, probably just ahead of Genbu's Kabuto as VIT is a secondary modifier.
From a ninja perspective, just as much use as the other two. Many katana ws's are multi hit so obviously the accuracy helps..alot. STR has obvious application.
Shura Kabuto +1/NQ will be beaten easy by Champion's Galea from new expansion, if you can get to hold Champion’s Galea by any chance…
Champion’s Galea base status: DEF:24 HP+15 "Counter"+3 Agument: STR+4 WS Acc+15 and STR+2 Haste+2% Total status: STR+6 WS Acc+15 Haste+2% and DEF:24 HP+15 "Counter"+3 (Comment Score: -8, keep on going with the minus ;))
As you can see the price for this cursed item dropped from 500k to 250k and price continue to decrease