A-110-4 is a so-called Thru Zero Quadrature VCO. The term "quadrature" means in this context that the oscillator outputs sine and cosine waveforms simultaneously. The main advantage of the A-110-4 compared to other Thru Zero VCOs is that the design uses a sine/cosine core which results in very pure waves with a minimum of distortion and overtones.
VCO analog Doepfer A-111-3 Micro Precision VCO€ 160
The Micro Precision VCO is a space-saving and utterly precise analog VCO/LFO with a extremely big frequency range, immaculate tracking over at least ten octaves and nearly perfect waveforms.