Charismatic and Financial are my favorites. Cha is my favorite warmonger trait; I love the flexibility it offers - it's not limited to 2 types of units, and you can choose the extra promotions. It's also great for building up super-units. The extra happiness is gold in the early part of theg ame as well, it gives you a little more flexibility for whipping early on. Finanacial is my favorite economy trait, because I think it's the most outright powerful of the economic traits, and being able to get three commerce from riverside cottages early on is huge. If you get any floodplains or lakes in your starting area you'll have heaps of food, great production from whipping, and lots of commerce as well.