Like David I have had almost all of them and out of the ones connected to Charlie Hall including all the Alesis models, his Hall & Collins is the most authentic. Of the Alesis models only the GT allowed the guitar to sound as it should, simply because of mis-matched input and output issues on the Quadraverb Plus, Q2 & Q20, as they were not really designed to be used in the way we used them. It was when I realised what was happening that the sound came back.
I briefly tried a tape Meazzi which was quite authentic soundwise but the one I tried had the rgular head spacings and would really have needed major surgery for it to suffice. Same too the Dynacord, great sound but heads all wrong for Shadows patterns. The Binson was OK for some tunes and I bought the Catalinbread on the strength of this, it's an improvement on the real Binson as it has varispeed plus a couple more head combinations and is great sounding - I like it a lot.
As for the Zoom collection, there are some good ones there too. The G3 being my favourite, the BT-100 (which I have for back up) and it's smaller siblings and G7lut were all very useable.
I have two Copicats, one is a four head IC300 and the other a Varispeed IC400, bothe very useable.
My favourite is my Klempt Echolette, not perfect head timings but more useable than the similar Dynacord. I use that in my studio for fun, having parted with my ESE Echomatic, which was superb. I just didn't gig it because I had my Vox Tonelab all set up for our show, echoes, chorus, distortion, tremolo, reverb, compression - everything - it works best for me.
I recently retired the Vox Tonelab in favour of the Line 6 Helix, it does the same job but a lot better.
I also still rate very highly the eTap2 hw, which sounds as good as anything I've owned and yes I did own the TVS3 and moved it on.
So after all of that which would I have between an Alesis Q20 and the Hall & Collins ?
My choice is the H&C, but I still prefer my Line 6 Helix for my job.