I was wondering if there’s any difference in look, feel and/or quality between these hole plugs when they’re installed.
I’m aware of the fact that the Sanwa ones are snap-ins and the Yenox ones aren’t, but both are fine for me. 
Who cares what the quality is? A plug is a plug, just a piece of plastic to block a hole. As long as it fits and when tightened down sufficiently- does not move around.
So assuming they fit, i’d grab the yenox’s because i know they’d be cheaper. On my last stick mod i used them in place of happ plugs, worked great, and they were a good 75 cents or so cheaper at lizardlick.