Really they're all useful in the right sitiuation. I voted creative just because it's usually not all that useful. It doesn't really help with a culture victory, border expansion is rarely an issue (i <3 stonehenge and libraries), and i rarely build theaters. BUT if you're playing with the max number of civs on the map then it's decent to help preserve your borders, so there IS an up side to it.
Expansive can be nice at times, but it's more circumstantial to what the map generator throws at you. if I have 5 different health resources between my first three cities I doubt that extra health bonus will ever really matter.
Protective... eh, it's nice if you're planning on pissing off the world or if you love Drill. I rarely give drill to anything, so it doesn't thrill me.
Imperialistic - I love this trait. great generals make war just that much easier and half price settlers are awesome. yes, it's mostly an early game boost, but anything you boost in the early game has a trickle down effect to everything else. not something to be scoffed at by any means.
Spiritual - actually one of my favorites, and I really don't know why so many people are voting for it. the more you micro manage the better you'll do. this boosts your micro managment ability. it makes a little less of a difference on marathon, but it's still useful.
Organized - I'd rather have financial?
very useful if you're going for conquest though. i think it'll make an even bigger difference after BTS if you plan on having overseas colonies. half price courthouses are great too.