The extra armour on Wrynn Dynasty beats the small amount of stamina on Timewarden's. The difference is 9 stam vs 250 armour, and the armour will at least equal the EH from that stamina, if not surpass it. Effective health relies on stamina and armour (and shield block value, which the Wrynn Dynasty Greaves have a very miniscule amount of too), not just stamina stacking.
Aside from that, I'd advise you to get the chest first if you have the badges. The belt is very good though, so get that next. And use Wrynn's, an upgrade is an upgrade