The one that you are comfortable with using and makes the type of finds that you are satisfied with at the end of the day.
I am not trying to sound like a wise guy but there is no one perfect detector for as I have said over the years, if there were all the other companies would be out of business. Want to start and argument? Ask some truck owners which brand is best and see the feathers fly!
Raw detection depth is just one piece of the overall success formula . . . . if it were the only one then the serious hunters would be using PI units in trashy parks to make sure nothing was overlooked but as we know, that simply is not an option to consider. Over the years I have kept detailed records of the better finds I have made (not counting clad and the like) and to be honest, a greater percentage have come from 8" or less but in high trash or areas where multiple targets are close together. When the Deus was brought to the US, it was clear that target separation was where it stood out from the crowd but as others have said, that was the basis for its design by Alain and his team.
Detection depth did not match the E-Trac / CTX 3030 but you were comparing a 9" coil to an 11" coil so there was some bias built into that comparison. XP worked on designing an improved coil and the 11" coil was born . . .now you are comparing apples to apples so to speak. They were able to keep the target separation better than anything else out there while adding very little to the weight and gaining inches in depth. Now, on actual in ground, undisturbed targets, comparisons can be made. On extremely deep silver (high conductive targets), the Minelab machines tend to produce a stronger signal than the Deus but if you are listening for those marginal signals and use your brain to determine if they are worth digging, you can get 10" deep dimes with the Deus. Where the scale starts to tip the other way is on the lower conductive targets starting with Indian Head pennies and lower . . . here the Deus has the detection depth edge as the FBS circuit is tailored for the higher conductive targets hence the "Silver Vacuum" tagline. There are some settings that I have found are standouts for deep targets in less trashy areas that put the two neck in neck when it comes to depth.
The target separation is where the Deus pulls ahead. There is a reason people opt for TTF on the Minelab and it is to compensate for the nulling or recovery time lag that exists on the FBS processor. Being able to separate targets and analyze them allows one to pull keepers from the trashy sections of sites that others avoid.
It all comes down to what features you want, what is comfortable in your hands and what you are finding . . . . I know some very avid hunters that have never changed from a Garrett Ace 250, Tesoro Silver Sabre, White's Coinmaster GT or the like and have a blast whenever they go out. Use what works for your style of hunting and when you come home with a smile each time you know you have found the PERFECT DETECTOR for you . . . . . OK, stepping down from my soapbox
Andy