What is your opinion? Can't decide.
I was wondering the same. I went for the intelijel and it seems great I've never used the others listed here. Other options are the Tangle Quartet or that Zlob one which is 6 vca in 8hp I believe?
I like quad VCAs that have a "separate" sum/mix output like the Doepfer A-135-1 (if you have the room) and the Bubblesound VCA4p (crowded panel but still patchable even with right angle cables!)
Many quad VCAs have a mix output on channel 4 but channels are subtracted from the mix as you patch into them. I like to run all 4 VCA outputs to separate channels on a stereo mixer for panning and then run the separate VCA mix output to processing modules like delay, reverb, Rings, etc
I have the intel Quad VCA and highly recommend it. Sold my Veils for it. 3db boost is crucial for mixing modules with lower output levels, and it sounds nice overdriven. Separate CV & gain offset attenuators is a big step up from the other 2 you listed. But if you want to save some HP check out the ALM Tangle Quartet. Straightforward routing and only 8hp.