No problem. But for a more technical explanantion:
I find Opeth's song structure amazing. When I first heard Bleak, I was introduced to a band that to me had a style all their own. From death metal growling to clean vocals. A drummer's sound I consider the sweetest - incredible fills with a jazz feel. Long songs that don't appear long - I never get bored listening to them, and many times I don't want the songs to end even after 10 minutes.
Seeing them live strengthens my feelings for them. They are as clean and amazing live as in the studio. Their musicianship shines on stage.
There are only a handful of bands that I love practically their entire catalogue - Opeth, Led Zeppelin, Grip Inc. Other bands I may like many songs, but not with the complete feel of the aforementioned. And of the 3 bands I listed, Opeth stands tall. They are sophisticated, powerful, gripping, emotional, and amazing.