The vocals on PL aren't any more harsh than The Odyssey.
I strongly disagree. Other than the title track and part of one other, Russ doesn't vary from harsh mode the entire album. I mean, it's not
more harsh than, say, King of Terrors. But it's like 90% of the album stays in that mode, which is fine if you like that kind of singing. I do, but I also like Russ' melodic side as well as all the vocal variety he is able to bring. PL has a great, heavy sound to it. But at the same time, it bores me because it almost never strays from the same exact sound you are hearing right from the first track.
Birchboy, not to throw a monkey wrench or anything, but I am going to offer completely different recommendations. You like heavy, and if you've listed to The Odyssey (the album) all the way through, you will have heard a pretty broad range of the band's sound, so I would definitely go with PL next. My only criticism of it is, again, the fact that it is very one-dimensional. But I suspect you would like it.
After that, V would be my recommendation. If you can get past the silly theme (mythology, etc.), it's probably their best album. Although I've definitely heard
heavier things, the opening two tracks are the most metal album opening I've ever heard in my life. The album is well put together in almost every respect. If I had to compare the album's sound to something else, I would compare it to the title track of The Odyssey. If you like the way it sounds, you will most definitely like V.