Again, these kind of have different applications!
The Sadowsky and Aguilar are essentially outboard versions of active electronics, that would usually be found inside active bass guitars. The Sadowsky will make your bass sound like a Sadowsky bass, the Aguilar will make your bass sound like one equipped with their OBP preamp (i.e. Spector, Modulus, etc...). The Tone Hammer actually has the OBP-3 box inside when you open it up!
The Sansamps however, as the name suggests, are intended to make your plain DI sound as though it's actually being played through an Ampeg stack! More of an amp simulator in that respect.
They're definitely different beasts, so it really depends what you want from this type of pedal.