"user" feels quite descriptive and neutral to me. It's a person that uses the device they own or are given access to. That's it.

I'm the (super-)user of my Linux PC. I have total ownership and control over it.

Arguably "customer" makes the business relation to the provider of a service/device clearer.

The term I hate with a burning passion is "consumer".

Definitely agree on your last point, "consumer" is by far the most passive of the terms, and wholly represents the current idea that companies can simply shovel out anything, because "consumers" will simply consume either way. Of course this isn't magic, a single person won't change just because you call them a user or a consumer, but it reflects your view of them, and will inform your actions towards them.

"customer" represents a two-sided relationship, and I do feel that "user" is kind of one-sided, but gives agency, a user will use a product for their own purposes, presumably to help them achieve some kind of goal. A "consumer" is completely passive, their main goal is to do what the company tells them to do. A customer can walk out of the relationship, a user might complain about problems they have with your product, but the consumer will simply continue consuming whatever you want them to consume.

The worst part though, they seem to be mostly correct in their assessment.