<< they cant sing about anything but dark evil stuff, >>
Sigh. Some people just don't get it. Have you actually read the lyrics? Have you been to any of their shows? Although many of Tool's fans think of them as just another heavy metal band, Maynard is really reaching out to the people who are listening in his lyrics. They are catarthic and cleansing. They create an atmosphere of release and, I quote, "urge you to take this feeling... and in the coming weeks, use it to create something positive in yourself."
When was the last time Patrick in Filter sang about something that had any meaning at all? (Hidden or otherwise). When was the last time he sang about some that wasn't dark? At least if you strip out a layer or two, Tool is ultimately an uplifting band. There is nothing to strip away with Filter. It's pointless chest-beating. "I'm so tough." "I'm so angry." They really have nothing to say.
I own and have analysed every album by both bands. Filter rocks. But that's all they do.