I have one of the "good" Ngk before they cheapened them up. The Ballenger version would be the way to go.
Before William got into the nines, I spent a lot of time helping him. I struggled for months trying to figure out why his car was running so well but the 6.1 chip was adding fuel all the time when the car looked like it was getting fuel.
I asked him if he had ever put leaded gas in the car since he got the AEM. He did not recall having done so, but, I told him to buy a new sensor and stick it in the car. Suddenly everything started behaving right and made sense. I am sure he must have put some leaded in the tank at some time but it could have simply been the heat that got to the old sensor. Either way, I prefer NGK
If I were buying an AEM, it would be the new faster responding version. I have always wondered how much "advance" you should put in the fueling to account for the lag.