Any of the Sansamp pedals (the VT Bass, VT Bass Deluxe, VT Deluxe, PDDI, BDDI, BDDI Programmable, BDDI Deluxe) will give a good SVT sound. The model you pick will depend on how much on stage flexibility you want. If you just want an "always on" SVT sound, get one of the less expensive pedals with fewer other options.
Because I wanted an SVT sound AND a Tube sound, I opted for the BDDI line of products, and am happy with the result.
TECH 21 - SANSAMP