I switched from Xfinity to Frontier fiber about two years ago. Xfinity overloaded the nodes in our neighborhood which led to extreme instability and network time outs, during the time everyone went WFH.

I went from 30-50ms latency to Google's DNS to a steady 6ms. Huge upgrade. Then about six months later, I had two instances where we were out of internet for 2-3 days. The communication to their tech support was extremely basic, and even after telling them my background in network engineering, it was the usual "turn it off for 2 minutes and back on again". I get it, most people calling for tech support need basic support, but I was also coming off of Xfinity PTSD. Luckily it seemed the issues were sorted out and haven't had an issue since.

So other than the initial hurdles of getting it installed in your area, it's been great. The mixed things you've heard about Frontier most likely has to do with Frontier DSL, which is a different section of Frontier completely.