Hard to choose, but if I had to, it would be the Bit 01 - only because you'll get more satisfying pads and chords from it. Bit 01= 2 osc. VS VX90=1 osc. The VX has to reduce polyphony to three notes for dual oscillator sounds - not fun (but I have heard of a sub-oscillator mod). The Bit unfortunately does not allow for filter FM and LFO PWM, only velocity to PWM IIRC, nor does it feature a unison mode like the VX or earlier Bit synths (One and 99). It does do nice splits and layers, though - and can save those configurations as performances.
After reading your posts for some months now, it seems as you've been wanting a pad machine, and the Bit is quite nice like that. The VX, to me, is more of a raw, electro machine.
“I have stretched ropes from steeple to steeple; garlands from window to window; golden chains from star to star, and I dance.” - Rimbaud