just make a build that u like and enjoy killing mobs in rifts. Then when something drops make a new build that evoles around that shield.
You dont have any influence after all what you will get from rifts or from gambling. Just take it one step at a time ;-)
Get the Cache one : "Covens Criterion" the 40-60% redux dmg on blocked attacks is unequalled in power.
The Westmarch Defender is better damage I guess; but the Covens Criterion is easier to farm (its in the same set as the gloves of worship and illusory boots so act II bounties (double check this I could be confused), and basically means any blocked attack does 0 dmg On the basis that if having 50% (average) dmg redux doesn't bring the hit into your block amount range; then unblocked hits must be smahsing your face in...