I have a standard THF barbarian approaching lvl 12. Up to this point, I took the low hanging fruits from each barbarian tree, usually grabbing as many powerful cores as possible (for example, at lvl 9 I had 11 points in each class tree, and 3 in human).
I know what enhancements work at 20.
But.. what to use in the teens? Level 12 is near, and so are T5 enhancements. What did you take while leveling? It seems to me that many T3 and T4 barb enhancements are rather meh, requiring me to waste a lot of AP to get to the sweet T5 stuff.