Few would dispute that most units around today - and there are many to chose from - are based in some way on the original Vox and Crybaby designs.
Although the two designs appear almost identical cosmetically, they differ substantially in terms of electronic filter design, and subsequent sound characteristics. It's generally thought that the Vox sounds very open and vocal-like, whereas the Crybaby is more aggressive and 'sharper' sounding. This perhaps goes some way to explaining why the Vox has been associated over the years with the singing lead styles of players such as Eric Clapton and Jimi Hendrix. The Crybaby, although still favoured by many lead players, has particularly won the hearts of rhythm-guitar players due to its highly percussive and penetrating, almost hollow sound. Just take a listen to the percussive wah-wah effect (made by muting the guitar strings) occurring throughout Isaac Hayes' theme song for the 1971 film 'Shaft'.