FiOS is a stellar TV and broadband product when folks that know what they're doing are maintaining it. It simply can't be beat. Frontier is not
one of those folks.
When we switched from Comcast to Verizon FiOS years ago we couldn't have been happier. Verizon made Comcast's service (both customer and delivery) look like they were in the stone age. However once Frontier took over they knowingly and unknowingly screwed things up beyond belief. Switching back to Comcast was a no-brainer only in that the frustration with the incredible incompetence of Frontier made even Comcast seem preferable.
Being an audio and videophile I'd be the first to complain about quality and perhaps Frontier has upped their game since we left, but with respect to HD Comcast's signal is about equal to FiOS and there are a few more HD channels that we wanted that Frontier didn't offer. HBO Go works fine on our iPads, etc. but we don't take advantage of it too often. Comcast's reliability has been rock-solid (unlike it was when we had them years ago).
Comcast's current download broadband speeds (after they boosted them a year ago or so) are about triple that of Frontier's in our neighborhood. Uploads are about half as fast though. Speed varies depending on the time of day, users on the headend, etc., but it's pretty steady overall.
All of that said, I firmly believe that all cable companies are the spawn of the devil. Only since the market has become competitive have any of them made the slightest effort at improving what they do or caring what their customers think.
Would we go back to Frontier? Hell may be freezing over at the moment, but probably not. OTOH (even though we think they are traitors for leaving) if Verizon were to come back into the market and pick up where they left off we'd drop Comcast in a heartbeat.
Still working on cutting the cable and the day is getting closer but it's not here just yet.