Well, I s'pose that is what it eventually comes down to...
Okay, I gotta give it to you RT folks ~ you've got some pretty perspicacious ears.

Just about everybody who took a guess figured out that Amp A was the Dr. Z and B was the Speed Twin. Kudos to y'all on that.
As for which I prefer, that's actually tough (I keep going back & forth), hence this thread.
I was surprised at how close I was able to get the Speed Twin's clean channel to the Z's cleans, but I did thing the Z ultimately had a better clean tone ... More depth and richness; the ST's clean channel was a little stiff by comparison.
On the dirty side of town, I'm surprised that that the Speed Twin didn't fare better, though a couple folks did dig the LOUD ST clip.
Perhaps I'm just not used to such an uncompressed amp, but the Z, particularly when boosted, seemed to me to walk a fine line between "bright" and "raspy," *especially* at average and lower volumes. Cranking the Z seems to remove a lot of the rasp, but I guess side-by-side, the ST's overdrive sounded a bit muffled or muddy. At least, that was Mrs. Draelyc's comment.
Of course, I normally run the Speed Twin through my Greenback-loaded 2x12, and I didn't change any of its settings when I ran it into the V30 1x12 for these clips, so perhaps that may explain some of the muddiness?
At any rate, thanks very much to all the folks who took time to listen and comment ~ MUCH appreciated!
And I'd love to hear from everyone else, too, so if you get a chance, take a listen & lemme know whatchoo tink, 'k?
Thanks!
Chris