Rage prevents you from casting spells, that means Githyanki spell kit is not that effective for a barb. I think gnomes are among the best races for barbarians right now because gnome cunning solves wisdom saving throws and let's you dump it, which is huge. Reach should not be a problem for a barb since they get + movement speed at level 5 and they can throw things while out of reach.
Jump requires an action, rage a bonus. Gith barbs cast jump then rage and leap incredible distances to engage the enemy and protect your squishies. Jump isn't concentration. Gith make pretty good barbs.
But really half orcs just suit it thematically and mechanically, don't they? I'm definitely planning a half orc barb at some time. Ugly and brutal, intimidating every time I can, great axe strictly only.
