It probably doesn't make any difference. I think all of the above would have enough horsepower to maintain the USB timings. It doesn't take much, until you start loading up a bunch of sticks, and then the problem is more to do with OS scheduler timings interleaving than with CPU/RAM.
Thanks @sidehack.
Should you daisy chain 2 GekkoScience BaseHubs together and plug it in the RPi or should you connect each GekkoScience BaseHub to a separate RPi? Or should you just plug 2 GekkoScience BaseHubs to 2 different USBs on the same RPi?
Also which OS is better on the RPi for the GekkoScience BaseHub with better OS scheduler timings, Raspian or Ubuntu?