There is only one company that has actually developed ASIC mining hardware that they are capable of shipping: ASICMINER. Avalon has delivered a good percentage of their pre-orders, but they are only selling bulk chips now.

Every other company currently claiming to sell ASIC devices is taking pre-order money and hoping to be able to develop the chips in the future, ie the BFL strategy. KNCMiner for example can claim to be as efficient as they want, like BLF did at first, as they have not actually produced working devices yet.