While the tech behind FiOS is supposed to be better the company behind it is not, and its implementation is not.. perhaps in a few years the answer may change, but for now...
#1 - Optimum iO
While FiOS gets some points for the availability of a multi room DVR, anyone can accomplish this with any video source and a one time charge of $100 to buy a wireless video sender and IR extender at radio shack. The Interactive programming, and local news channels (NY 1 and channel 12 plus 612 channel 12 interactive) are only available on iO. I haven't heard many complaints from people about being billed for channels that they never ordered with iO opposed to FiOS where there are many documented cased on the net about people complaining of being billed for channels never received or ordered, only to have the charges re-appear on the bill for several months afterward, having to call for credit on a monthly basis.
#2 Optimum voice, a second line can be added for around $15, and if you make international calls, world call can be added for around $30 for unlimited international calling. While FiOS does provide a battery back up, this too can be accomplished with OV and OOL by purchasing a UPS (uninterpretable power supply) from any office supply or electronic store, and depending on your budget, you can have much longer back-up time then that provided by the FiOS battery back up system.
#3 Optimum OOL. while the potential for faster speeds is available with a direct fiber optic line, FiOS speeds are currently limited (likely this is a marketing scheme so they can charge more for faster speeds in the future) the fact is OOL boost which is $10-15 a month more then the base OOL package gets speeds up to 30/5 for much less then the same speed provided by FiOS. OOL boost also includes free web hosting, domain name registration and unblocks port 80 so that you can host a server on your internet connection. For businesses, for an additional $30 above the base OOL package you get OOL boost plus a static IP. FiOS charges about $100 for a static IP and nothing else! FiOS also does not allow you to host a server on your internet connection.
ALSO... installation... while it may be true that many cable TV installers are sub-contractors, and the work that they perform might not always be up to your standards, all that is required is the installation of RG6 coax cable to your TV's and modem, most of the wiring should already be in place from previous cable service working at that location... I would not recommend them doing any phone wiring, as they suck at phone wiring installation. FiOS requires a long installation, the fiber cable needs to be installed from the pole to your home, a large ugly ONT (optical network terminal) needs to be installed on the side of your home. Some of your existing wiring might be able to be used, but they may need to replace some of the RG6 coax, and will need to run a low voltage wire from the ONT to near an outlet inside your home for the battery back up, they may also need to run CAT5 wiring.
The modem/router that is provided with FiOS is a pain to work with, and is not very user friendly...