Go with Power Build Up, its alot more effective and has other uses apart from end drain. Anyone thats ever teamed with my Kin/elec knows how good this is. Watch out for Rad corruptors, Elec Brutes and anything else that has end drain protection running. In PvE use Power Build Up, Short Circuit then Fulcrum Shift followed by Lightning Ball. 
Power Build up can be combined with both Short Circuit and Transferrance one after the other, boosting the drain on both.
So for drain, on Kin/Elec, you'll get more milage out of Power. It also does lots more as well as just boost your drain, it's all round an excellent power. Added to which Total Focus is significantly better than Thunder Strike, due to the bloody great stun on it.
Just wondering what the best Epic pool would be for a kin/elec "sapper" build, to go for maximum sappage.
More specifically, is the combination of Power Build Up and Short Circuit as good as or better than the combination of Power Sink and Short Circuit, in terms of drain, convenience, etc.?