It seems a common pattern that a business gets big enough, dominate through network effects and/or regulations and high barriers to entry, and then their services and customer support deteriorate to awful levels. But they end up being the only major game in town, so consumers begrudgingly use them.

That's the common pattern I see, at least.

So I'm curious about the opposite - are there any businesses that are relative monopolies in their industries that you're happy to use / do business with?

I'm struggling to come up with an example myself. Are monopolies doomed to become awful to consumers?