Well, considering I have only owned two other machines besides my new Deus, that is a tough one. My self-built Heathkit detector has many fine memories considering I was also to hit public areas that had never been touched by the detector, finding some interesting coins, including an 1893-S half dollar. But Whites 6000 Series 2 produced a lot of silver, especially dimes.
Keep in mind I am on the west coast of the USA, so no Roman coins for me!