We had FIOS since it first arrived on LI, in fact, we were the first town to get it. Then the bills started creeping up each year. And The Verizon billing department kept screwing with our bill. I felt like I was talking to them every other month about some other stupid charge that I didn't order. Their customer service SUCKS!
When Optimum finally woke up and offered a similar package at a deeply discounted rate about 2 years ago we switched back. Yeah, there was a period of adjustment, but we are mostly happy now.
The Optimum boxes and menu is a bit slower to respond. I see no difference in picture quality or internet speeds. Plus they have News 12, which my wife likes.
Now it is 2 years later and our promotional offer has run out. The cost for Optimum and FIOS is about the same for our service. Optimum will not discount our contract even after I threatened to go back to FIOS. Overall, I think FIOS is more convenient and may be slightly better, though I dread dealing with their customer service group ever again - WHICH BLOWS DONKEY DICK!
So we are trying to decide which way to go also at this point. No way to get the actual $'s down, just which service is better for us.