What skill should i choose

Concentration should usually be maxed, there are some builds that put it on 1.
Neither Wolf Fang Fist nor Spin Rush should be maxed. There is just too much SP intake for those attacks to become useful.
If you have extra SP, but them into:
Big bang attack, Hitrate Passive, Kaioken, or even Storm Strike (I am assuming you have both needles maxed)

Quote from B4.DA.$$

Concentration should usually be maxed, there are some builds that put it on 1.
Neither Wolf Fang Fist nor Spin Rush should be maxed. There is just too much SP intake for those attacks to become useful.
If you have extra SP, but them into:
Big bang attack, Hitrate Passive, Kaioken, or even Storm Strike (I am assuming you have both needles maxed)

And doge rate debufff and constituation Debuff kaioken isn't that good for pvp same for big bang

Quote from TheProdige

And doge rate debufff and constituation Debuff kaioken isn't that good for pvp same for big bang

well, he didn't say what kind of build he's going for, and tbh, The constitution debuff is a waste of 4 SP in my opinion.
The Same for Glitz! Though the Dodge Passive is nice... but I assume he maxed that

Concentrated Kamehameha is good for a quick KD skill. Final Flash also deserves some love since it can be a stronger substitute to Tunnel Slash for luring mobs...provided you aim right.