Where are you going to go metal detecting? If you plan on buying another Tesoro (with more knobs) then it is a pretty simple process of deduction. In order of pricing:
Relic Hunting: Cibola, Outlaw (8" coil), Vaquero, Outlaw (3 coil pack), Tejon.
Saltwater Hunting: all relic machines above (on dry beach sand) Sand Shark (wet sand).
Fresh Water Hunting: (all Tesoro metal detectors' coils are submersible) Tiger Shark (for fully submersible treasure seeking).
Coinshooting: all Tesoro metal detectors except Tiger Shark and Sand Shark (those are more specialty machines) (common ones are Compadre, Silver Umax, Deleon (probably the best one) and Cortes, followed by the relic machines listed above.
Honestly, all Tesoro metal detectors can do the job, it is that some excel more than others for varying detector situations! Most common machines individuals buy are the Compadre, Cibola, Vaquero, Silver Umax, Deleon, and the newest detector to come out besides the Vaquero would be the Outlaw!
P.S. as you can see in my Signature Block, I do like Tesoro Metal Detectors!