I'm gonna be odd man out and say definitely take TWO Barbarian levels but stop there. What you're really after is rage, unarmored defense, and that sweet sweet RECKLESS ATTACK. No 3rd level Barb feature is worth giving up Survivor for, and I'd say that the 2 levels of Barb would be worth giving up the 4th attack capstone.(for a Champion)

Survivor is great though. Regen 10 hp every round when you're hurt is super strong.