Humans are a safe bet, but tieflings bring more to the table. You get +2 to INT and CHA, both of which are excellent for the CW, and the racial gives you +5% damage to mobs that are below fifty percent, so a 2.5% damage increase overall. The extra three feats for humans don't give you the same amount of flat, easy to calculate extra damage, since the choices (at least for a renegade CW) for those three extra feats are all more subtle and situation-dependent.
But you can pick whichever race you like and will do fine.
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But you can pick whichever race you like and will do fine.