At the present time, we cannot choose a path to specialize in, so I wouldn't worry about it too much. Honestly, I think Kodius did too good a job distributing awesome abilities down every path, it's very hard to choose one and say "you should do this" :). I wouldn't worry about it for the moment, and choose my abilities piecemeal as they appeal to you.

In general, there are entry-level abilities on each tree which I think are "mandatory" for all young barbarians, so I'd focus more on rounding out your selection of abilities and making sure you can train all three of our skills (debilitation, augmentation, warding), so make sure you have a roar and one of the warding forms/meditations.

Whenever the ability to pick a path is coded, Kodius didn't specify what exactly that will do, but brainstormed a couple suggestions (lower slot costs, better IF management for those abilities). it's not like choosing one path will lock you out of the other trees.