
Originally Posted by
Yokai
If you keep a BMG on swap in every loadout, and especially if you also have the Preparedness buff in your loadouts, then it becomes feasible to use a higher capacity shield regardless of its delay or recharge rate. When you take too many hits and your shield needs to come back, you just swap to BMG and right-click to heal yourself. Using a BMG on yourself recharges your shields on demand and very fast. Also, because of the Preparedness perk, your main damage weapon is being reloaded at 9% every second while you're regenning your own shield manually this way. You can swap right back and keep firing.
If you're not doing any of the above, then a Respark shield is IMO the only viable shield to use. Period.
Edit, the approach outlined above is also true if you're in a co-op with a dedicated healer. They keep your shields topped off while you blaze away and "tank" out front for the team.