No that would be Opeth. I love Porcupine Tree but there are tons of bands better than them, Katatonia, Symphony X, Dream Theater (as a whole) etc.
My feeling is that the best progressive bands aren't metal bands. They are progressive rock bands. And the best metal bands are mainly committed to the riff and the power and/or darkness and/or energy of metal. The most interesting thing about the Porcupine Tree show I saw was that the dude didn't wear socks while he mercilessly ripped off the Pink Floyd songs I grew up with.
I'm not sure who's heard what, but some progressive rock that I adore---
Close to the Edge & Drama by Yes.
Court of the Crimson King, Larks Tongues in Aspic, Islands & Red by King Crimson.
There's the Rub & Argus by Wishbone Ash
Animals & Dark Side of the Moon by Pink Floyd.
Minstrel in the Gallery & Thick as a Brick & Stormwatch by Jethro Tull
Interview & Three Friends by Gentle Giant.
Cherry Five & Roller by Goblin.
One Size Fits All by Frank Zappa
Darwin by Banco
Ut by New Trolls
Once the sound stage is defined by heavy riffing guitars---as it is in HEAVY METAL---it overpowers the mix of instruments and is the focus alongside dramatic singing and (in extreme metals) drumming, which is a lot of what I like about metal.
Other than Katatonia--who I like, but are closer to Depeche Mode and the Cure in spirit since the Discouraged Ones---most of these prog metal bands don't work for me. They split the difference of two things I adore and give me the rewards of neither genre.
Emperor's IX Equilibrium is one of the only truly progressive metal albums I dig. Also, Anacrusis, Screams & Whispers.
Opeth, Fates Warning, Spiral Architect, Watchtower...meh. This does not go as far a Crimson did 40+ years ago and is not as powerful and empowering as Megadeth is on Rust in Peace or Destroyer 666 is on Phoenix Rising or Mayhem is on Wolf's Lair Abyss.