Five O'Clock People - 11 Years (1999-Present)
Michael W. Smith - 14 Years (1996-Present)
Audio Adrenaline - 14 Years (1996-Present)
P.O.D. - 11 Years (1999-Present)
Luna Halo - 10 Years (2000-Present)
I considered listing some of these.
I discovered Five O'Clock People in 2000 by complete accident, after a friend heard me recommend Five Iron Frenzy, got confused, and ordered the wrong CD from Columbia House. She ended up liking
The Nothing Venture, and so did I. Sadly, of all their releases to date, it's still their only full-length, so I felt funny saying "I've been a fan for 10 years" when I spent large chunks of that time not thinking about them at all.
Similar story for Luna Halo, minus the accidental stumbling across. I liked Reality Check before them, and figured a new band with some of the same dudes couldn't be too bad. (It's worth noting that current Luna Halo has as much in common with original LH as original LH does with Reality Check.)
I became an MWS fan in 1994, but became a non-fan in 2001. His instrumental album was the last thing he did that I actually cared about.
I picked up and then dropped Audio A at around the same time frame as MWS. Nothing after
Lift did anything for me.
I first heard P.O.D. in 1997 (anyone remember 7Ball Magazine?), then heard more of 'em when
Southtown came out in '99, but didn't like 'em until 2001. I'm iffy about them nowadays, but I like enough about their albums to keep buying 'em. Still, 9 years of liking a band is nothing to sneeze at, and with the turmoil they've been through, I'm actually surprised they're still around
and have their original lineup intact.
If liking a solo artist back when he was part of a band counts, then I've been a fan of Steven Delopoulos for 12 years.
There aren't more "secular" bands on my list because I didn't become OK with actively listening to any of that stuff until circa 2000. I had a roommate who was into Barenaked Ladies back in 1996, so I
suppose I've liked them that long, though I didn't get into them in earnest until about 2001. Similar story with Dave Matthews Band. And I guess U2, which I first heard as a kid, and kind of liked back then even though I didn't know each time I heard them that it was the same guys.
NP: "Burn That Broken Bed", Iron & Wine/Calexico