Tool would be the band, but metal would be the genre.
My best friend was a huge Tool fan in high school and begged me to go see them back in 96' then again a year or so later and I refused, saying all their songs were just "whispering verses and screaming choruses". WAAF was playing Tool nonstop and I just hated them. My head was so far up Steve Vai's ass that I simply didn't give a shit about songwriting or anything outside of guitar technique. It wasn't until Lateralus came out and the same buddy said, "You're going to listen to this song and if you're not a fan after this, you hate music.". Begrudgingly, I complied. During our weekend ritual of sitting in his truck in my buddy's driveway getting baked, he put "Lateralus" on....by the time it came to the end section ("With my feet upon the ground..." that KILLER polyrhythm with the bass whammy part) we were car-moshing and I've been hooked ever since. But for a good 5-6 years, I hated Tool.
And metal in general took me a long time to get into. I grew up on Floyd, started playing guitar at 11 and only listened to Gilmour and Eric Johnson. I got into AIC shortly after and that was probably the catalyst, then Dream Theater some years later. Screaming vocals, though, took me so long to get into and it wasn't until I walked into my old drummer's bedroom and saw Watch It Go 3 playing on his VCR that I instantly became a fan of all things metal. My personality changed, I wanted to act like Dimebag all the time.....but all I did was drink like him for 15 years after.