My all time favorite band is either Sick of it all or Tool. Though I go through phases of not listening to them for months on end. Both of these bands I have been into for roughly the same time (about 5 years or so) and I never get bored of them. However I also have current favorites, bands that I am listening to a lot at the moment. Currently these are Pelican, I just got their first self-titled EP Paint It Black, Recently got the Paradise 12'' and its magic Nothing Done, really good simple old school hardcore.