Excal 1000, Excal II, Sovereign GT, CZ-20, Tiger Shark, Tejon, GTI 1500, Surfmaster Pulse, CZ6a, DFX, AT PRO, Fisher 1235, Surf PI Pro, 1280-X, many more because I enjoy learning them. New Garrett Ca
Depending on the area you would like to hunt, the ten inch coil will cover more area and get deeper too. When your searching farm fields or non trashy sites it lowers the odds of you coming home empty. It also helps if you had ground balance.
My fisher comes with a 11' inch coil that just kills it even in the trashy areas. But owning a 10" coil for my older Bounty Hunter was only used for parking lot scans, and large field areas. The ten inch coil I have does go deeper. Buying a coil is easier than a new detector. The 10" coil was a lil heavy for the shaft, but still hit the coins.
FYI: If you goto my profile. I started up a you tube channel and I tested the difference between the 4" sniper & the 10" concentric. I hope that helps ya out. Ehh.... maybe not. The 4" sniper really REALLY shines over the 10" I have found.