Without running large, well structured tests, it would be difficult to justify blanket statements about speed and reliability.

As an anecdotal observation, I'm in a Comcast and FIOS area. At the store we have Comcast in an inner city area and there are several outages per year. I can't comment about speed because we have a lower tier of service. At my suburban home I have FIOS and it has been years between outages. In terms of customer complaints we have more complaints from our Comcast users, but the overwhelming majority of our customers use Comcast. We had one customer switch from FIOS to Comcast, but many have switched or are itching to switch to FIOS. The single switch to Comcast was an elderly gentleman who had Comcast at the shore and couldn't deal with the differences in the FIOS cable box interface at home.