I think that shields would be a very good opportunity to create relevant gameplay choices. Taking some inspiration from Overwatch's variety of shield-centered skills, having some variety could really create interesting choices:
Basic Shield: 360 degree, medium radius, health-based with low idle energy consumption, higher energy consumption to refill when damaged.
Antimatter Shield: 360 degree, medium radius, can absorb any amount of damage, but extremely high energy consumption. Perfect to block huge damage spikes.
Energy Barrier: ~135 degree wall, big radius, health-based. substantially beefier than the basic shield. Can only regenerate when not taking damage for at least ~1 second. Well suited for short to medium defense periods against directed attacks.
These are just examples - the basic idea would be to play around with shape/coverage, idle/active energy consumption, damage negation models (health-based, infinite absorption, reflection etc.) and other values to create a range of interesting choices.
