The beautiful but slightly puzzling thing about Opeth, at least in my experience following the band for a bit more than two decades and seeing all kinds of opinions about their music, is that there's rarely any consensus on which their best albums are. With most other bands I know, at least a big part of their fanbase tends to agree on that, but with Opeth it's different. There are the die-hard fans of the first two albums (which are quite different to the rest in many respects), the "My Arms, Your Hearse in the only truly balanced album between older and newer Opeth sound" fans, the classic, perhaps more abundant Still Life & Blackwater Park enthusiasts, the many who consider Ghost Reveries to be the best thing they've ever done, the "clean vocals only" listeners who only enjoy Damnation and their post-2008 output...
And you know what? All of them are right. I honestly don't think there are any drastic differences in quality between their albums*, despite the sometimes very notable stylistic differences. I do believe the individual preferences have more to do with personal tastes in this case. I wouldn't say this about most other bands/artists. At the same time, this has made me realize that I cannot trust any review of their music, not even to get a very general idea of how it sounds. I've heard so many completely opposite views about a given Opeth album or song that it's an exercise in futility.
*I have to make an exception: I honestly think Sorceress is a failure both in songwriting and production (and the 5.1 mix sucks).