Stick with Verizon FiOS. I have had Verizon FiOS for over a year and it comes loaded with a huge array of HD channels (more than I can keep up with), and the internet is blindingly fast. I love having lightning-speed internet and crystal-clear high-definition channels (including MLB TV, NBA TV, NFL TV, Showtime, MTVHD, etc). It is a reliable service.
I was truly bummed to learn how Dolan screwed Verizon over and that MSG HD was not available on Verizon FiOS. You will just have to get used to watching the Knicks in SD... it sucks, but it's not worth losing the fast internet-speeds and other HD channels for. Additionally, every so often (such as last night) when the Knicks are featured in a nationally televised game, you can always catch them on ESPN.
my 2 cents