Since at least a couple of people asked about FiOS, I thought I would share my experience with the whole list.
I have had Verizon FiOS phone and Internet for over three years, and I am generally happy with it. I recently added FiOS TV, and I am less impressed with it, but it is no worse Comcast cable and you save money on bundling all three services.
Phone: No notable difference for everyday use. Note, though, that they cut your copper wire when you switch to FiOS. This means that the phone line is no longer self-powered, and you may lose phone service during extended power outages. You do get a battery backup, so this is typically not an issue in practice, but it is something to be aware of.
Internet: There is a notable speedup compared to DSL. The difference is most notable for uploads, for example if you upload photos or videos to some Website. I have found the service very reliable.
TV: The multi-room DVR feature is nice, but we haven't used it much to be honest. The On Demand menu is very different compared to Comcast. The content is about the same, but it often takes longer to navigate to the program you want to watch. I am not that impressed with the overall user experience, and we have had some issues with the DVR not recording the final minute of some show. The big plus is really that you can save money by bundling services (or you can get more for the same amount of money). I believe there are also more HD channels with FiOS. For example, I used to get only one HBO channel in HD with Comcast, but FiOS gives me all HBO channels in HD, so I guess that is pretty nice. Overall I don't regret switching from Comcast TV, but I am not as impressed as I wanted to be.
Support: I have actually had good experience with technical support. Verizon technicians seem more knowledable than Comcast technicians, but that could just be a coincidence.
In conclusion, I would get FiOS for the Internet alone, and the other services just because it is convenient to have a single provider and it saves money.
--Haakan