The impaler! Recharge delay 1.99 and a capacity on 49k, at least that's my version. Downside is the recharge rate, about 4k
Any decent shield with Hyperion parts can get a pretty low delay. Tediore and Dahl parts also give lower delays, though not quite as good as Hyperion. Also, do you mean 49k after skills/badass rank? Highest I could get was 43k capacity with 1.99 recharge.