The XS is the Sovereign that made Minelab so popular with the coin hunters. This detector comes with the 8 inch Coinsearch coil that also was the best coil Minelab made for the Sovereigns, but was not waterproof like the BBS and the new Tornado coils.
I feel the XS is still the most sought after Sovereign series as far as used. The GT is the next most popular too I feel as it seem to be a bit more sensitive than the others are. Unlike some of the others the Elite is the one Sovereign I didn't like as much as the others as they changed the placement of the controls and found I kept turning the wrong controls. I also felt I never seen the depth I did with the other Sovereign, tried 2 different one and felt they were the same.
I sold my GT and will get another back in the spring, but still have a XS on my wall and probably always will have a XS in my battery of detectors.