I had Fios fwith my Tivos for a couple years while living in Texas. What I really loved about the service, besides the television quality, was that Cablecards were paired to the account and not the set-top-box so I could upgrade Tivos and/or use the Cablecard with an infrequently used Television, etc. While I didn't like not having On Demand, it really wasn't a big deal since we recorded just about everything.
Here in Virginia I've been with Comcast for the past few years because I keep getting a great promotion offer renewed every year (all the digital channels plua HBO, SHO, MAX, Starz, TMC and 150MB Internet for $119.99) and love the XFinity On Demand App that Comcast downloads onto the Tivos (Premiere and Roamio). I would probably switch-over the Fios (it's also available in my area) but they won't price match Comcast and I don't believe they have an On Demand app for the Tivo. Anyway, I have several Tivos with lifetime...may get a Bolt+ if Tivo les me lifetime (aka All In) the Roamio for a modest fee. We shall see.
I've used a ton of DVRs over the years from Dish, DirecTV, Sony and more and the Tivo smokes 'em all IMO.