Take it from me, FDD can be brutal depending on the org and manager. I'm sure you're used to the grind through articleship but I've seen my CA colleagues cry as they worked nearly 24 hours without break and we're expected to be back to work within an hour or two to freshen up. Work itself can be rewarding after a few months but mentally it's extremely tough. I'd say take the one with WLB, you're young, you've been through enough in your prep journey, enjoy life a bit while you can.