I have not heard any complaints about outages or connection problems on Frontier fiber.

The thing with Frontier is they have two separate services - Frontier DSL and Frontier Fiber. They bought the DSL rights from AT&T a decade or so ago, and it's terrible - mostly because the infrastructure is 100+ years old, and they aren't going to invest billions into replacing it. DSL in general is an inferior technology for high speed internet anyways.

Fiber on the other hand, is brand new. All the lines are run brand new, with direct fiber lines all the way to the street in front of your house. Plus it has a much higher bandwidth. Cable internet also works excellently (unless you care about high speed upload), so it really comes down to cost. There is also GoNetSpeed fiber optic available in some towns, depending where you live.