The build and sound quality of these pedals is beyond reproach, making them a good choice for studio work. Many tonal flavours are accessible via both pedals, but they have a different level of focus on certain production effects, so be clear what your requirements are before you buy. The vocoder has a consistent quality to its many available sounds and the ability to vocode with a mic alone is amazing.
The TC-Helicon VoiceTone Synth is a really well thought out well-engineered pedal that gives fast and easy access to all your favourite vocal excesses. VoiceTone Synth is capable of some first-class vocal effects and is highly recommended.