Noble level? Ok here goes:
Trait pool (un-ordered)
Aggressive - Imperialistic - Protective - Charismatic - Industrious - Financial - Organized - Spiritual - Philosophical - Creative - Expansive
1. Industrious. The BEST trait to have on noble. On prince and up the other civilizations start getting wonders faster due to their faster research and improved production, but an Industrious leader on noble level can very possibly build EVERY wonder in the game, if they so wish. Heck, I play as Saladin (Spiritual, Protective) and still managed to snag every single wonder when I used to play at noble.
2. Spiritual. This trait is not much use if you're a total pacifist or a total warmonger, but if you're a builder/warmonger hybrid (like myself) this trait assumes a level all of its own - switching between economy and war civics at will, with no anarchy, is nothing to joke about. When you declare war on a non- spiritual, pacifist leader with your war civics on, and he's on economic civics, he won't be able to change his civics without risking much (if he does, take advantage of his stupidity and conquer his now no-defensive-bonus cities due to anarchy
). Many spiritual civilizations also start with Mysticism, allowing them to grab a religion easily.
The rest of them depends on whether you're running a conquest or builder strategy. For war get aggressive or protective (if protective, run crossbow rushes - very effective). I didn't mention charismatic because it favors a builder more than a conqueror. If you want to build, snag organized, expansive or charismatic. Charismatic allows bigger cities earlier on due to the happiness bonus, but in the long run Expansive is more beneficial because it allows bigger cities later on due to the health bonus. Those two and organized are around the same usefulness really.
I've never played around with Creative, Financial, Imperialistic and Philosophical much so I can't really comment on them, but it's my strong belief that Creative is a rather sub-par (no offense intended to the trait's fans) trait to use for anything other than a cultural victory. You don't really need Theatres and Colosseums for any other victory, and early libraries is almost nothing compared to the benefits the other traits can confer.