I prefer the reference client to other implementations. Offline tx would be nice.

Possibly a way to do it with Bitcoin-Qt is to setup a cleanly installed machine/Ubuntu USB flash drive with the full blockchain, take it offline and then copy your encrypted wallet to it. Sign a tx, burn the wallet to CD and copy it to another clean Ubuntu instance. From that second instance you would never sign a tx or message. View only. The decryption key would never be released into memory. Let it download the blockchain. It will broadcast the tx.