Over in Japan, the SNES Classic (Super Famicom Classic) is doing quite well for itself, having sold 368,000 units in its first four days of release -- yes, that's quite a lot of dough for a system that houses decades old games. For comparison's sake, the NES Classic (Famicom Classic) sold 262,000 units over the first four days when it launched in November of 2016.
Although there's plenty of speculation to be had as to why it did better, the sheer numbers are all in favor of the NES, which sold better than the SNES in nearly every region in the world. No, it's likely due to enhanced stock, as Nintendo actually did deliver somewhat when the SNES Classic hit retail -- whereas the NES Classic presence was almost non-existent at brick and mortar locations.
Hopefully they'll keep pumping them out and not halt production altogether like they did with its predecessor (although Nintendo claims they're going to make more NES Classics, it's yet to be seen).