Personally speaking, timing and phrasing are qualities that serve me well.
I'm not a strong singer and I have yet to get serious about exercising my vocals but I do try to write to my strengths or rather, not to accentuate my weaknesses.

I believe, if you have timing and phasing, which I feel is key to comfortable breathing, in the pocket,your foundation is set.
Tweaks to things like pitch and energy or style, can help in making the vocal more enjoyable. Pitch is one of my weaknesses.

I think I'll go with Timing and Phrasing.