We live in an old GTE area of North Texas. Got my first GTE landline phone in 1981 when I was 20. Verizon bought GTE around 2000. They laid fiber on my street in 2006. As soon as it was lit, I subscribed to FiOS internet and phone. TV service came a few years later IIRC.
By the time Frontier took over FiOS a few years ago, we were down to internet only. Landline is Google Voice VoIP and TV is all streaming. The internet service is still rock solid. We pay $55/mo for 50/50. In 13 years, I can only recall one outage, which was a hardware failure at our house (ONT died). They rolled a truck the next day to replace it. Bandwidth is extremely stable. Speedtests are consistently 58/58 with pings around 3-5ms.
Yes, Frontier's phone service is the worst. Our local nextdoor.com has no shortage of threads with people complaining about billing issues, price increases, and poor responsiveness from phone reps. No one really complains about the services themselves. Just changes that don't get made correctly, resulting in billing issues that never seem to get resolved.
Fortunately, we rarely make many changes, so no reason to call. I've called Frontier maybe twice. It's always a circus, but with patience, I've always been able to get my issue resolved in a timely manner. We're also fortunate to have a good alternative here in Charter/Spectrum. We now have access to 200/20 for about $45/mo (new customer rate). I would have no issue switching if anything changed with our FiOS service.