I couldn’t give you comparisons to the three you provided, but I’ve been using the Synergistic Research PowerCell for a few generations of its release now. I started with the PowerCell 12 UEF SE with the blue outlets and a SR Atmosphere Level 3 power cable. It was a welcome move from my PS Audio P5 Power Plant which I had previously. Between those two units, i felt the SR PowerCell was more natural, where the PS Audio was a bit more shrill.
With the PowerCell 12, I was even plugging my amplification to it, and I preferred it vs being plugged directly in wall. That said, I once tried hooking up four hungry amps in addition to all my other electronics and it did go into protection mode (not critical, I just had to power it down and up again), but at least I know it had its limits.
Last year I upgraded to the PowerCell SX with the Galileo SX cable. Dynamics improved, and current delivery was obviously better. I’m not sure how much to attribute to the PowerCell SX itself or the upgraded SX power cable. I’ve since purchased a few Galileo SX ac cables for my amp and preamp, and they too have made a notable difference over my previous aftermarket cables.
in full transparency I also use almost a full loom of Synergistic Research Galileo SX cables at this point, except for the power and interconnects going to my subs.