Id recommend Bitinstant at this time because its pretty clear that Coinbase is working with the Feds - i.e., all their data is provided to DHS, FBI, CIA, NSA, IRS...
Thats how they secured another round of venture capital - $5M I believe. They bent over for Uncle Sam to keep the doors open.
I'm not happy with bitinstant - they STICK it to you with hidden fees greater than their initial fee by giving you a LOUSY price point on the dollar to bitcoin exchange rate WAY outside the trading range.