Customer service is completely unimportant unless you need to use it. Then it becomes very important.
I had occasion to call Benchmade customer service about a new knife I had purchased. This was 8-9 years ago. An actual human answered the phone. She did not transfer me or put me on hold. I explained the issue to her, and she gave me the exact instructions over the phone on how to fix the problem. She was friendly, polite, and understanding in addition to having the technical knowledge required, so I did not end up feeling like an idiot. No issues with the knife ever since. That was good customer service.
I have never needed to call Zero Tolerance/Kershaw, Buck, Case, Spyderco, Victorinox, GEC, or the other manufacturers whose knives I have purchased. I have asked Case a couple of informational questions via their "contact us" web form and received adequate responses via e-mail each time. So those are all makers for whom it has not (yet) mattered to me if they have good customer service or not.